Author Archives: Priyanka

In This Post we are  providing Chapter-7 STRUCTURAL ORGANIZATION IN ANIMALS NCERT MOST IMPORTANT QUESTIONS for Class 11 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON STRUCTURAL ORGANIZATION IN ANIMALS

Question 1.
Enumerate the various functions of epithelial tissue.

Answer:
Function:

1. Protection: It protects the underlying or overlying soft tissues against heat, injury, chemicals, virus and bacteria etc.
2. Absorption: It absorbs the digestive food especially with columnar cells of the intestine.
3. Secretion: The glandular epithelial cells lining the inner cavities secrete various substances like mucous, enzymes and hormones which are necessary for various metabolic activities.
4. Excretion: The epithelial cells of kidney tubules and sweat glands help in the excretion of wastes from the body.
5. Sensation: The nerve ending in the epithelial cells of the retina, olfactory organs and nasal chamber etc. receive the stimuli from the external atmosphere and transfer them to the brain for interpretation.
6. Other functions: The trachea contains the ciliated epithelium to facilitate the transport of mucous and other substances from one part of the body to another. The lungs’ epithelium helps in the exchange of gases during respiration and the germinal epithelium of testes and ovaries form the sperms and ova respectively. The epithelium also forms the exoskeleton structure as scales, feathers, hairs, nails, claws, horns etc.

Question 2.
What is a gland? Differentiate between simple and compound exocrine gland.

Answer:
Any organ or structure that secretes specific useful substances is known as a gland.

A gland develops from the epithelium tissues and is generally cubical, short columnar or polyhedral in shape.
1. Simple exocrine gland: Simple exocrine gland has no branch but consists of a single unbranched duct lined by epithelial cells. The secretory part of the gland also consists of epithelial cells arranged in a simple tube, coiled tube in a flask which send their secretion into a single duct.

So these are simple tubular glands, simple coiled tubular glands and simple alveolar glands respectively.

2. Compound exocrine gland: Compound exocrine gland has a branched system of ducts. The secretory part consists of tubules-Com-pound tables, many acini or alveoli-compound alveolar glands or a combination of both tubules and acini-compound tubuloalveolar gland.

Question 3.
What is connective tissue? Give its important functions.

Answer:
Connective tissue is mesodermal in origin and form of matrix, fibres and cells. It constitutes the extracellular ground substance and fills up the intercellular spaces between the cells.

Functions of connective tissue: The connective tissue perform various functions and these are:

1. It serves the function of packing material nearly for all organs.
2. It binds one tissue or organ to another and serves the purpose of a strong elastic rope.
3. It provides skeletal support and shape to the body.
4. It protects the vital organs of the cranial and thoracic cavities, deep blood vessels and nerves from mechanical injuries.
5. The adipose connective tissue stores fat and represent stored energy.
6. It provides defence against foreign particles like bacteria. The phagocytes of leucocytes ingest the bacteria and germs and protect the body against infection.
7. The lymphocytes from the antibodies against the action of antigens and provide immunity to the body.

Question 4.
What is adipose tissue? Where does it lie in the human body? Give its important functions.

Answer:
Adipose tissue: It is the specialized form of areolar tissue where it contains fat cells or adipocytes in the matrix. Each fat cell is large, rounded occupied by big fat droplets and its nucleus and cytoplasm are pushed towards the periphery of the cell. This imparts a ‘signet’ ring-like look to the fat cell.

These fat cells can easily be stained by Sudan III or osmic acid. The matrix is supported by a loose framework of areolar tissue containing fibroblasts, macrophage, white collagen fibres of small size, elastic fibres; lymphatics and blood vessels.

The lactating tissue lies in the subcutaneous tissue of the skin, in the mesentery and in the perinephric and sub periodical tissue of the body. The lactating mammary gland of human also contain abundant amounts of adipose tissue but these are quite lacking in penis, scrotum, eyelids and in the cranial cavity.

Adipose tissue

Functions: It synthesises, stores and metabolises the fat and forms the insulating layer beneath the skin. It collects around the viscera especially kidneys and prevents them from shock and injury.

Question 5.
Plasma contains three classes of proteins. What are these? Give their functions.

Answer:
The major classes of plasma proteins are

1. Albumin,
2. Globulins and
3. Fibrinogen

Functions of Plasma Proteins:

1. The immune bodies are mainly an important constituent of the globulin fraction which provide defence against infection.,
2. Fibrinogen and prothrombin are necessary for the coagulation of blood.
3. The plasma proteins normally have an osmotic effect of 25 mm Hg and thus influence the exchange of fluid between blood and tissue spaces.
4. Plasma proteins mainly globulins are responsible for the viscosity of blood and this help in maintaining peripheral resistance and arterial blood pressure for efficient heart functioning.
5. Plasma, proteins act as buffers in maintaining acid-base balance.
6. Albumin and globulin proteins retain water in the blood plasma by their osmotic effects and their deficiency lead to oedema.
7. Plasma proteins especially the fibrinogen are concerned with erythrocyte sedimentation rate.
8. Plasma proteins help in the transport of certain substances like hormones, enzymes, iron and copper etc. in the blood.
9. Plasma proteins distribute heat uniformly all over the body.

Question 6.
Describe briefly the external features of cockroach.

Answer:
The cockroach is a nocturnal cursorial and omnivorous insect. It is generally reddish-brown in colour and its entire body is covered by tough chitin. Its body is divided into head, thorax and abdomen.

Head: It is somewhat pear-shaped and is six segmented. It lies at a right angle to the body with the broad side upwards. It articulates with the thorax by the flexible neck. On each side of the head is a large compound eye. A pair of antennae articulate Inspite close to the notches of the compound eyes.

The top of the head is termed a vertex. Mouthparts are chewing and surrounded by five kinds of appendages. These include, the labrum, mandibles, first maxillae, second maxillae and hypopharynx. The neck is slender, flexible and supported by chitinous cervical plates.

Thorax: The thorax consists of three segments – Prothorax, mesothorax and metathorax. Each segment of the thorax is covered by four sclerites. There is a tergum on the dorsal side, a sternum on the ventral side and a pleuron on either lateral side.

The thorax bears three pairs of jointed walking legs, a pair per segment and two pairs of wings in meso and metathorax. Each leg is made of a number of parts-coxa; the trochanter, femur, tibia and tarsus. Their leg is made of a number of parts coxa, trochanter, femur, tibia and tarsus: They are formed as lateral expansions of the

(a) External features of cockroach

integument between the tergum and the pleuron. Each wing is supported by a network of hollow veins. The mesothorax wings are narrow, thick, opaque and leathery and not used in flight.
Head

(b) External features of cockroach

Abdomen: The abdomen is ten segmented and covered by four sclerites. There are is all ten-terga, but 9th terga of the male and 8th and 9th terga of the female are covered by 7th tergum. In the female-only the first seven sterna are visible, the seventh, eighth and ninth sterna together form a brood pouch.

The 10th tergum bears a pair of a long tapering structure called anal cerci. In male 9th sternum bears a pair of short unjointed anal styles. They are absent in females. The gonapophyses are very small, irregular arising from the 9th sternum in the male and from the eighth and ninth sterna in the female.

At the posterior end of the abdomen, below the tenth terga, is situated the anus. There, are ten pairs of spiracles on the lateral sides of the body, two on the thorax, eight on the abdomen.

Question 7.
Describe briefly the alimentary canal and digestive glands of the frog.

Answer:
The alimentary canal of the frog is short. It starts with a mouth that is terminal in position. It opens into the buccopharyngeal cavity which contains the maxillary and vomerine teeth and carries the openings of the eustachian tube, vocal sac, gullet and glottis. The gullet opens in a narrow and short tubed Oesophagus which continues In the large stomach. Stomach walls arc highly muscular that help In converting the food into chyme.

The stomach is followed by a coiled small intestine. The small intestine bears a number of finger-like folds called villi and microvilli which increase the surface area for absorption of digested food. Intestine continues into a wider section, opening into the cloaca. The urinary bladder opens into the cloaca. The urinary opens into the cloacal chamber through the ureter.

Alimentary canal and digestive glands of the frog

The gastric glands of the stomach bring about the digestion of protein. The liver secretes bile that is temporarily stored in the gall bladder. Bile helps in the digestion of food by changing its pH from acidic to alkaline and by emulsifying the fat. The liver does not secrete any enzyme. The pancreas is situated in a thin mesentery and lies parallel to the stomach.

It secretes pancreatic juice that causes the digestion of protein starch and fats with the help of trypsin, amylase and lipase. Similarly, intestinal juices with their peptidases, lipase and sugar enzymes bring about the digestion of peptides, fats and sugars.

Question 8.
Describe briefly the blood vascular system of the cockroach.

Answer:
The cockroach has an open circulatory system. Blood is colourless and contains plasma with colourless cells, the leucocytes. It does not contain haemoglobin and thus, plays no role in respiration.

The heart is thirteen chambered which is long, narrow, muscular and tube-like structure. The three chambers of the heart lie in the thorax and ten in the abdomen. The posterior end is closed and the anterior end is continued forwards as the anterior aorta. It opens into a haemocoel in the head.

There is a small hole, the Ostia at the posterior side of each chamber. Ostia is guided by valves to allow blood flow only in one direction i.e., from the haemocoel to the inner chamber of the heart.

All the visceral organs are bathed in blood. It consists of a colourless liquid part, plasma containing many corpuscles called haemocytes.

Question 9.
Describe the male reproductive organs in the frog.

Answer:
It consists of a pair of the yellowish testis that is attached to the upper part of the kidneys by a double fold of peritoneum called mesorchium.

Reproductive organs of the male frog

Each testis contains about 10 to 12 vasa efferentia that run through the mesorchium and enter the kidneys of their side. In kidneys, these open into the bidder’s canal that finally joins with the urinogenital ducts. This cones of the kidneys and finally opens into the cloaca. The cloaca is a small, medium chamber that is used to pass faecal matter, urine and sperms to the exterior.

Question 10.
Describe the alimentary canal of an earthworm and interactions with mankind.

Answer:
Alimentary canal of earthworm: Alimentary canal is a straight tube starting from 1st segment to the last segment of the body. It consists of the mouth, buccal cavity, pharynx, oesophagus, gizzard, stomach, intestine and anus. The mouth lies in the first segment.

The mouth opens into the buccal cavity (1 – 3 segment). The buccal cavity leads into the pharynx. The pharynx leads into the oesophagus which is continued into the gizzard. The stomach extends from the 9th 14th segment. The intestine starts from the 15th segment and continues up to the last segment. The alimentary canal opens to the outside by an aperture called the anus.

Interaction of earthworm with mankind:

1. Earthworms are the friends of farmers. They make burrows in the soil and make it porous to facilitate respiration and penetration of plant root. Earthworm increases the fertility of the soil by vermicomposting.
2. In China, Japan, Burma, Australia, earthworms are used for food.
3. Earthworms are used as bait for game fishing.
4. In India, earthworms are used for the treatment of stones, jaundice, piles, diarrhoea.
5. Earthworms also cause harm by making burrows in the land (damage tender plant).

Alimentary canal of the earthworm

In This Post we are  providing Chapter-6 ANATOMY OF FLOWERING PLANTS NCERT MOST IMPORTANT QUESTIONS for Class 11 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON ANATOMY OF FLOWERING PLANTS

Question 1.
What is phellogen? What does it produce?

Answer:
Phellogen is a cork cambium that is developed front hypodermis and epidermal cells near to the cortex. It is produced in the dicot stem during secondary growth for providing protection to the inner tissues.

It produces cork towards the outside and secondary cortex towards the inside.

Question 2.
What features make wood unique as a material?

Answer:
The following features make the wood unique as a material:

1. As it is light in weight, it can be easily transported over long distances.
2. It is a bad conductor of heat, electricity and sound.
3. It is resistant to rust.
4. It can be moulded into various desirable shapes.
5. The fluctuation in temperature does not affect largely and the volume of the wood.
6. Wood pulp is used for the synthesis of various materials like paper, plastics, rayon and transparent films.

Question 3.
List few important anatomical characteristics of the xerophytic leaf.

Answer:
The anatomical characteristics of the xerophytic leaf are:

1. The presence of a thick cuticle on both the epidermis of the leaf offers protection and reduces the rate of transpiration.
2. A multilayered epidermis is present. Its cells are elongated and lignified.
3. Stomata remain sunken in the lower epidermis. This reduces the rate of transpiration.
4. Palisade tissues are richly filled with chloroplast.
5. It also contains crystals of calcium oxalate scattered in the upper palisade tissues of leaf cells.

Question 4.
List the differences between the internal structure of the dicot stem and the Monocot stem.

Answer:

Dicot Stem	Monocot Stem
(i) Multicellular epidermal hairs are present.	(i) Epidermal hairs are generally absent.
(ii) Hypodermis is made up of collenchyma cells.	(ii) Hypodermis is made up of sclerenchyma cells.
(iii) Cortex is distinct and made up of parenchyma cells.	(iii) Cortex is not distinct but instead ground tissue is present.
(iv) Endodermis and pericycle are present.	(iv) Endodermis end pericycle are absent.
(v) A large pith is present.	(v) Pith is absent.
(vi) The prominent medullary ray between vascular bundles are present.	(vi) Medullary rays are absent.
(vii) The definite number of same size vascular bundles are arranged in a concentric ring.	(vii) The vascular bundles are of different size are found scattered in the ground tissue.
(viii) The vascular bundles are conjoint, collateral and open.	(viii) The vascular bundles are conjoint, collateral and closed.
(ix) The sheath around the vascular bundle is absent.	(ix) Bundle sheath made up of sclerenchyma cells is present around the vascular bundle.
(x) Lysigenous cavity is absent.	(x) Lysigenenous cavity is present in mature vascular bandies.
(xi) Secondary growth is present.	(xi) Secondary growth is absent.
(xii) Phloem parenchyma is present.	(xii) Phloem parenchyma is absent.

Question 5.
What are the characters of collenchyma tissues? Give its functions also.

Answer:
Collenchyma tissue: Collenchyma tissue cells are living isodiametric without any intercellular spaces. The comer walls are thickened by Pectinisation. They appear cylindrical in vertical section and oval or polygonal in cross-section. The nucleus in each cell lies at a comer position.

Collenchyma

They are found in the dicot stem below the epidermis and on the outer region of the leaf, midribs and pedicels. On the basis of thickening, they are of three types:

1. Lamellar,
2. Angular,
3. Lacunate

Functions: Collenchyma tissue provides mechanical function as well v as the function of photosynthesis.

Question 6.
Draw a well-labelled diagram showing the L.S.of phloem of an angiosperm with its components

Answer:
Phloem is a food conducting tissue and it consists of:

1. Sieve, elements
2. Companion cells
3. Phloem fibres and
4. Phloem parenchyma.

1. Sieve elements: These occur as a single cell in pteridophytes and gymnosperms and longitudinal file of cells in angiosperms. The morphological specialization of sieve plates is the development of sieve area on their walls bearing sieve plates. The sieve plate bears a large number of perforations.

The protoplasmic strands maintain continuity through these perforations within the adjoining sieve tubes. In a mature sieve element there occurs a thin layer of parietal cytoplasm and a large central vacuole. The most important features of sieve elements are that they lack a nucleus at maturity.

Structure of phloem (L.S)

2. Companion cells: These are thin-walled, living parenchyma narrow cells, which are closely associated with sieve tube elements. They appear rounded or polygonal with dense granular cytoplasm, « prominent nucleus and numerous small vacuoles. The companion cells lack starch.

The nuclei of the companion cells serve as the nucleus of sieve tubes as they lack them. The companion cells mainly occur in angiosperms, ac¬companying the sieve tube elements.

3. Phloem fibres: They form a prominent part of both the primary and secondary phloem. They are elongated cells with lignified walls having simple pits. They provide support and help in the transport of food material. They are used for making cords and ropes etc.

4. Phloem parenchyma: These are the living parenchyma cells associated with sieve tube cells. They are elongated with sieve tube cells. They are elongated, pointed in shape and store the starch, fat and other organic substances. The tannings and resins are also found in these cells, They are elongated like the sieve elements.

The sieve element is a living component, which lacks a nucleus at maturity.

Question 7.
Describe briefly the various types of vascular bundles.

Answer:
These are of the following types:
1. Radial The bundles in which xylem and phloem are arranged on different adulterating with each other and form the separate bundles are called radial vascular bundles as in all roots.

2. Conjoint The xylem and phloem are situated at the same radius and form a vascular bundle together.

These are divided into three types:
(a) Collateral: These are the bundles where xylem and phloem are arranged on some radius, xylem is located internally and phloem externally. These may be open when there is a patch of cambium in between the xylem and phloem e.g. Helianthus or closed when there is no cambium at all as seen in monocot stems

(b) Bicallatiral: In this vascular bundle, the phloem is found in two groups one outside the xylem elements and the other inner to them. These are always open and found in pumpkin.

(c) Concentric: The bundle in which either Phloemounds the phloem completely is known as concentric.

This exists in two forms.

1. Anphicribral: The xylem lies at the centre and is surrounded by a ring of phloem, e.g., fern.
2. Amphivaial: The phloem lies at the centre and is surrounded by the xylem e.g. Dracaena.

Question 8.
Describe briefly the internal structure of the monocot root with the help of a labelled diagram.

Answer:
A transverse section of the monocot root shows the following issues.

1. It is composed of a single layer of compactly arranged thin-walled cells without intercellular spaces and cuticle. It bears many unicellular root hair.
2. Cortex: It is present beneath the epidermis. It consists of 15-20 layers of parenchymatous cells with large intercellular spaces.
3. Endodermis: It is the innermost layer of the cortex. Its cells are barrel-shaped with Casparian strips on their anticlinal walls. The passage cells are seen just opposite the protoxylem ends.
4. Pericycle: It consists of a single layer of thin-walled parenchymatous cells.
5. Vascular bundle: The vascular bundles are radial and the xylem is exarch. The xylem and phloem bundles are always more than six.
6. Pith: It occupies the central portion of the stele and is made up of parenchymatous cells.
7. Conjunctive tissue: It consists of parenchymatous cells and is found between the xylem and phloem strands.
   
   T.S. of a typical monocot root

Question 9.
Define the following.

(i) Radial vascular bundles
Answer:
Radial vascular bundles: The bundles in which xylem and phloem are arranged in different radii alternating with each other and form the separate bundles are called radial vascular bundles as in all roots.

(ii) Collateral vascular bundles
Answer:
Collateral vascular bundles: These are the bundles where xylem and phloem are arranged not at the same radius. Xylem is located internally and phloem externally. These may be open when there is a patch of cambium in between the xylem and phloem e.g. Helianthus or closed when there is no cambium at all as seen in the monocot stem.

(iii) Exarch xylem
Answer:
Exarch xylem: It is the condition where protoxylem is located towards the periphery of axis and metaxylem inwards e.g. root.

(iv) Endarch xylem
Answer:
Endarch xylem: It is the condition where metaxylem is located towards the periphery of axis and protoxylem inwards e.g. stem.

(v) Stele
Answer:
Stele: All the tissues that lie internal to Endoolerinis are collectively called stele. The outermost layer of stell is known as the pericycle.

Question 10.
Distinguish between:

(i) Phellem and Pheiloderm
Answer:
Phellem: It is a dead tissue that is formed by the activity of cork cambium in the outer region of the cortex during secondary growth. It is protective in function.

Pheiloderm: It is a living tissue that is formed by the activity of cork cambium in the inner side of the cortex. It regains during secondary growth. If performs the function of storage.

(ii) Open bundle and closed bundle
Answer:
Open Bundle: Avascular bundle containing cambium between xylem and phloem is called an open bundle e.g. dicot stem.

Closed Bundle: Avascular handle lacking cambium between xylem and phloem is called a closed bundle e.g. monocot stem.

(iii) Fascicular cambium and inter fascicular cambium
Answer:
Fascicular cambium: It is a strip of cambium found between the xylem and phloem of each vascular bundle of dicot stem.

Interfascicular cambium: It is a strip of cambium that is formed from the cells of medullary rays adjoining with the fascicular cambium. It occurs dining secondary growth.

(iv) Conjoint vascular bundles and Radial vascular bundles
Answer:
Conjoint vascular bundles: Xylem and phloem lie in the same bundles. They lie on different radii alternating with each other e.g. Dicot and monocot root.

Radial vascular bundles: Xylem and phloem lie in separate bundles. They lie on different radii alternating with each other e.g. Dicot and monocot root.

(v) Periderm and Bark
Answer:
Periderm: It includes three tissue consisting of phellogen, phellem and phelloderm and is formed at the peripheral region of the axis.

Bark: It includes all the tissue external to the secondary xylem formed during secondary growth. These are cambium, secondary phloem.

In This Post we are  providing Chapter-1 MORPHOLOGY OF FLOWERING PLANTS NCERT MOST IMPORTANT QUESTIONS for Class 11 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON MORPHOLOGY OF FLOWERING PLANTS

Question 1.
What are the functions of the root system?

Answer:
The main functions of the root system are as follows:
(a) Absorption of water and minerals from the soil.
(b) To provide a proper anchorage to the plant parts.
(c) To store reserved food material
(d) Synthesis of plant growth regulators

Question 2.
Write a note on different types of root systems.

Answer:
(a) In most of the dicotyledonous plants, the direct elongation of the radicle leads to the formation of primary roots which grows inside the soil. The primary roots and their branches constitute the taproot system. For example-mustard plant.

(b) In monocotyledonous plants the primary root is short-lived and is replaced by a large number of roots. Their roots originate from the base of the stem and constitute the fibrous root system. For example wheat plant.

(c) In some plants, roots arise from parts of the plant other than the radicle. Such roots are called adventitious roots. For example grass, banyan tree etc.

Question 3.
Write a short note on the stem.

Answer:
The stem is the ascending part of the axis bearing branches leaves, flowers and fruits. It develops from the plumule of the embryo of a germinating seed. The stem bears nodes and internodes. The region of the stem where leaves are born is called nodes while the portion between two nodes is called an internode. The stem is generally green when young and later becomes woody and dark brown.

Question 4.
What are the functions of petiole and lamina?

Answer:
Functions of petiole:
(a) The petiole helps hold the blade to light.
(b) It allows leaf blades to flutter in wind, thereby cooling the leaf and bringing fresh air to the leaf surface.

Functions of Lamina
(a) The veins of the lamina provide rigidity to the leaf blade
(b) It acts as channels of transport for water, minerals and food materials.

Question 5.
What do you mean by phyllotaxy?

Answer:
The pattern of arrangement of leaves on the stem or branch is termed phyllotaxy.

It is usually of three types:
(a) Alternate: A single leaf arises at each node in an alternate manner, as in a china rose.
(b) Opposite: A pair of leaves arise at each node and lie opposite to each other as in calotropis and guava plants.
(c) Whorled: When more than two leaves arise at a node and form a whorl, as in Alstonia

Question 6.
What is inflorescence? Name two types of inflorescences.

Answer:
The arrangement of flowers on the floral axis is termed an inflorescence

Types of inflorescences:
(a) Racemose: In racemose the main axis continues to grow, the flowers are borne laterally in acropetal succession.
(b) Cymose: In the cymose type of inflorescence, the main axis terminates in a flower. The flowers are borne in a basipetal order.

Question 7.
Write a note on the symmetry of a flower.

Answer:
The flower may be actinomorphic (radical symmetry) or zygomorphic (bilateral symmetry) in symmetry.
(a) Actinomorphic: When a flower can be divided into two equal radical halves in any radical plane passing through the centre, it is said to be actino-morphic, e.g., mustard, datura, chilli.
(b) Zygomorphic: When a flower is divided into two similar halves only in one particular vertical plane, it is said to be zygomorphic, e.g., pea, bean, cassia.

Question 6.
Write a short note on the fruit.

Answer:
Fruit is a natural or ripened ovary, developed after fertilization.

Fruit is called a parthenocarpic fruit if it is formed without fertilization of the ovary.

The fruit consists of a wall or pericarp and seeds. The pericarp may be dry or fleshy. If the pericarp is thick and fleshy, it is differentiated into the outer part called epicarp, a middle part called mesocarp and an inner part called the endocarp.

Question 7.
Write a note on the structure of a dicotyledonous seed.

Answer:
The outermost covering of a seed is called the seed coat. The seed coat has two layers, the outer testa and the inner tegmen. The developing seeds are attached to the fruit by means of a scar called the hilum, on the seed coat. A small pore called the micropyle is situated above the hilum. In the inner region of the seed coat is the embryo, consisting of an embryonal axis and two cotyledons. The cotyledons are fleshy and full of reserve food materials. At the end of the embryonal axis are present the radicle and the plumule.

Question 8.
Write a note on the regions of the root.

Answer:
At the apex, the root is covered by a thimble-like structure called the root cap. The root cap protects the tender apex of the root as it penetrates the soil. A few millimetres above the root cap is the region of meristematic activity. The cells present in this region are very small, thin-walled and with dense protoplasm.

The cells proximal to this region undergo rapid elongation and enlargement and are also responsible for the growth of the root in length. This region is called the region of elongation. The cells of this region gradually differentiate and mature. This zone proximal to the region of elongation is called the region of maturation. Some epidermal cells, from this region, form very fine and delicate, thread-like structures called root hairs. The functions of these root hairs are to absorb water and minerals from the soil.

The regions of the root-tip

Question 9.
Write a note of different types of leaves and phyllotaxy.

Answer:
When the lamina of the leaf is entire or incised and the incisions do not touch the midrib, the leaf is said to be simple. A leaf is said to be compound when the incisions of the lamina reach up. to the midrib breaking it into a number of leaflets. In both simple and compound leaves a bud is present in the axil of the petiole. However, a bud is not present in the axil of leaflets of the compound leaf.

There are two types of compound leaves:
(a) Pinnately compound leaf
(b) Palmately compound leaf

In a pinnately compound leaf, a number of leaflets are present on a common axis, the rachis, which represents the midrib of the leaf. However in palmately compound leaves, the leaflets are attached at a common point,
i. e, the tip of the petiole.

Phyllotaxy refers to the pattern of arrangement of leaves on the stem or branch. Phyllotaxy is of three types alternate, opposite and whorled. A single leaf that arises at each node in an alternate manner is called alternate phyllotaxy, for example, as in china rose. When a pair of leaves arise at each node and lie opposite to each other it is called opposite phyllotaxy, for example in calotropis. If more than two leaves arise at a node and form a whorl it is called whorled phyllotaxy, as in Alstonia.

Different types of phyllotaxy: (a) Alternate (b) Opposite(c) Whorled

Question 10.
Write in details about a flower.

Answer:
A flower is a reproductive unit in the angiosperms. It is meant for sexual reproduction. Four different kinds of whorls are found in a flower. These are arranged successively on the swollen end of the stalk or pedicel, called the thalamus or receptacle.

These are calyx, corolla, androecium and gynoecium.
(a) Calyx: It is the outermost whorl of the flower and its members are called sepals. Mostly the sepals are green in colour, leaf-like and protect the flower in the bud stage. The calyx may be gamosepalous (in which sepals are united or polysepalous (in which sepals are free).

(b) Corolla: It is composed of petals that are usually brightly coloured to attract insects for pollination. The shape of the corolla may be tubular, bell-shaped, funnel-shaped or wheel-shaped.

(c) Aestivation: The pattern of arrangement of sepals or petals in the floral bud with respect to the other members of the same whorl is known as aestivation. The main types of aestivation are valvate, twisted, imbricate and vexillary.

Types of aestivation in corolla: (a) Valvate (b) Twisted (c) Imbricate (d) Vexillary

(d) Androecium: It is composed of stamens which are male reproductive organs of a flower. Each stamen consists of a stalk or a filament and an anther. Each anther is usually bilobed. There are two chambers (pollen sacs) in each lobe. The pollen grains are produced in pollen sacs.

Position of floral parts on thalamus : (a) Hypogynous (b) and (c) Perigynous (d) Epigynous

(e) Gynoecium: It is the female reproductive part of the flower. It is made up of one or more carpels. A carpel consists of three parts ovary, stigma and style. The stigma is at the tip of the style and is the receptive surface for pollen grains. The ovary is an enlarged basal part. The style connects the ovary to the stigma. Each ovary bears one or more ovules attached to a flattened, cushion-like placenta.

A flower may be trimerous tetramerous or pentamerous when the floral appendages are in multiples of 3, 4 and 5 respectively.

The flowers are described as hypogynous perigynous and epigynous based on the position of calyx, corolla and androecium in respect of the ovary on the thalamus.

In This Post we are  providing Chapter-4 ANIMAL KINGDOM NCERT MOST IMPORTANT QUESTIONS for Class 11 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON ANIMAL KINGDOM

Question 1.
Describe the phylum Cnidaria.

Answer:
Cnidaria is aquatic, mostly marine, sessile, or free-swimming animals. The phylum name is derived from the stinging cells (nematocysts) or cnidoblasts present on the ectoderm of tentacles and on the body of these carnivorous animals. Cnidoblasts are used for anchorage, defense, and for capture of prey. Cnidarians exhibit tissue level of organization and exhibit radial symmetry. They are diploblastic.

The digestive system is incomplete. They have a central gastro-vascular cavity with a single opening, mouth. Digestion is extracellular and intracellular. Some of the cnidarians, e.g., corals, have skeletons composed of calcium carbonate.

Cnidarians exhibit two basic body forms called a polyp (e.g., Hydra) and medusa (e.g., Auralia). The former, a sessile and cylindrical form, whereas, the latter, umbrella-shaped and free-swimming. Those cnidarians which exist in both forms exhibit alternation of generation, i.e. polyps asexually produce medusae and medusae forming the polyps sexually (e.g., Ophelia)

Examples of cnidaria: Hydra, Porpita, Vellala, Physalia (Portuguese man-of-war), Aurelia (Jellyfish), Adamisia (Sea anemone), Pennatula (Sea- pen), Gorgonia (Sea-fan), and Meandrina (Brain coral).

Some cnidarians (a) Obelia (b) Jellyfish (c) Physalia (d) Sea anemone

Polyp and medusa body from (a) sessile poy (b) swimming medusa

Structure of Hydra

Question 2.
Distinguish between the Chordates and Non-Chordates.

Answer:

Chordates	Non-Chordates
1. Notochord present.	1. Notochord absent.
2. Central nervous system is dorsal, hollow, and single.	2. Central nervous system is ventral solid and double.
3. Pharynx perforated by gill slices	3. Gill slits are absent.
4. Heart is ventral.	4. Heart is dorsal.
5. A post-anal (tail) is present.	5. Past-anal tail is absent.

Question 3.
Explain the class amphibia.

Answer:
As their name indicates (Gr. Amphi, dual, double + bios, life), most amphibians can exist in aquatic as well as terrestrial habitats. Most of them have two pairs of limbs. The body is divisible into the head and trunk; the tail may be present in some. The amphibian skin is moist (without scales). The eyes have eyelids. A tympanum represents the ear.

The alimentary canal, urinary and reproductive tracts open into a common chamber called the cloaca, which opens to the exterior through an aperture called the cloacal aperture. Respiration may be by gills, lungs, or through the skin. The heart is three-chambered (2 auricles and 1 ventricle). These are cold-blooded animals.

Sexes are separate Fertilization is external. They are oviparous and development is direct or indirect.

Examples of Amphibia: Bufo (Toad), Rana (Frog), Hyla (Tree frog),

Salamandra (Salamander), Ichthyophis (Limbless amphibia).

Frog

Question 4.
Describe the class Reptilia.

Answer:
The class name refers to their creeping or crawling mode of locomotion. They are mostly terrestrial animals with a body covered by dry and cornified skin, epidermal scales, or scutes. They do not have external ear openings. Limbs, when present, are two pairs. The heart is usually three-chambered, but four-chambered in crocodiles, Reptiles are cold-blooded animals. The excretory organ is the kidney. Snakes and lizards shed their scales as skin cast.

Sexes are separate. Fertilization is internal. They are oviparous and development is direct.

Examples of Reptilia T Chelone (Turtle), Testudo (Tortoise), Chameleon (Tree lizard), Calotes (Garden lizard), Naja (Cobra), Crocodilus (Croco¬dile), Aligator (Alligator).

(a) Tortoise, (b) Monitor (Indian goh) (c) Naja (d) Crocodile (e) Chameleon

Question 5.
Explain the important characteristics of Mammalia.

Answer:
Mammalia is generally terrestrial, found in a variety of habitats- polar ice caps, deserts, mountains, forests, grasslands, and dark cover. Some of them have even adapted to fly or live in water. The most unique mammalian characteristic is the presence of milk-producing glands (mammary glands) by which the young ones are nourished.

Mammalia has two pairs of limbs, which are variously adapted for walking, running, climbing, burrowing, swimming, and flying. The skin of mammals is unique in possessing hairs. External ears or pinnae are present. Different types of teeth are present in the jaw. The heart is four-chambered. The lungs are well developed. Mammals show the greatest intelligence among all the animals.

Sexes are separate and fertilization is internal. They are viviparous with few exceptions and development is direct.

Some mammals:

Ornithorhynchus

Balaenoptera

Pteropus

Macropus

Question 6.
Describe the main characteristic of class-Aves.

Answer:
The characteristic features of birds are the presence of feathers and most of them can fly with few exceptions, generally called flightless birds (e.g. Ostrich). They possess beak. The forelimbs are modified into wings. The hind limbs generally have scales and are modified for walking, swimming, or clasping the tree branches. Skin is dry without glands except for the oil gland at the base of the tail. The endoskeleton is fully ossified (bony) and the long bones are hollow with air cavities.

The digestive tract of birds has additional chambers, the crop, and the gizzard. The heart is completely four-chambered. They are warm-blooded (homeotherms) animals, i.e., they are able to maintain constant body temperature. Respiration is by lungs that contain air sacs. Birds have a good sense of sight. The excretory organ is a kidney.

Sexes are separate. Fertilization is internal. They are oviparous and development is direct. Examples of Aves are Corvus (crow), Columba (pigeon), Prittacula (parrot), Struthio (Ostrich) Paver (Peacock), Aptenodytes (Penguin)

Some birds : (a) Neophron (b) Struthio (c) Psittacula (d) Pavo

Question 7.
Write some basic characterize- features of the following Phyla:
Ctenophora, Annelida, Mo.llusca, Echino Desmata and Hemichordata.

Answer:
Represents some basic characteristic features of different phyla.

Question 8.
Draw the diagram of the classification of phylum Chordata.
Answer:

Classification of phylum Chordata

Question 9.
Describe the phylum Arthropods.

Answer:
The phylum Arthropoda is the largest phylum of the animal kingdom consisting of more than 900,000 species, which include many economically important insects.

1. They have an organ-system level of body organization. They are bilaterally symmetrical, triploblastic, segmented, and acoelomate animals.
2. The body of arthropods is covered by a chitinous cuticle which forms the exoskeleton. The body segments are fused to form the head, thorax, and abdomen.
3. They have jointed appendages. The appendages are variously modified to form antennae, mouthparts, pincers (chelicerae), or walking legs.
4. The digestive system is complete.
5. Respiratory organs are gills, book gills, book lungs, or tracheal system.
6. The circulatory system is open type.
7. The nervous system is almost similar to that of the annelids. Sensory organs include antennae for perceiving odor, receptors for taste, eyes (compound and simple), statocysts or balance, organs, and sound receptors.
8. Excretion takes place through green glands or malpighian tubules.
9. They are mostly dioecious. Reproduction is sexual. Fertilization is usually internal. They are mostly oviparous.

Development may be direct or indirect, passing through many larval stages. The process of transformation of a larva into an adult is called metamorphosis.

Some common arthropods (a) Centipede (b) Millipede (c) Beetle (d) Prawn (e) Spider and (f) Scorpian

Examples of Arthropoda: Araneus (Garden spides), Limulus (King crab),

Buthus (Scorpion), Scolopendra (Centipede), Cancer (Common crab), Balanus (Barnacle), Lepisma (Silverfish), Periplaneta (Cockroach), Apis (Bee) Anopheles (Mosquito), Musca (Housefly), Charaxes (Butterfly), Attelabus (Beetle), Locusta (Locust) and An ax (Dragonfly).

Question 10.
Describe the phylum Porifera.

Answer:
Members of this phylum are commonly known as sponges. They are generally marine, diploblastic bilaterally symmetrical with a significant water transport mechanism. They are considered as very primitive multi-cellular animals and have a cellular level of organization.

Water can enter through minute pores (Ostia) in the body wall directly or through the canal into a central cavity, spongocoel, from where it goes out through the osculum.

This pathway of water transport is called the canal system and is helpful in food gathering, respiratory exchange, and removal of water. Choanocytes or collar cells line the spongocoel and the canals. Digestion is intracellular. The body is supported by a skeleton made up of spicules or spongin fibers.

Sexes are not separate (monoecious/hermaphrodite/bisexual), i.e., eggs and sperms are produced by the same individual. Sponges reproduce asexually by fragmentation and sexually by the formation of gametes. Fertilization is internal and development is indirect having a larval stage that is morphologically distinct from the adult.

Examples of Porifera are Sycon (Scypha), Spongilla, Chalina, (Dead man’s finger), and Euspongia (Bath sponge)

Examples for Porifera: (a) Sycon (b) Euspongia (c) Spongilla

In This Post we are  providing Chapter-3 PLANT KINGDOM NCERT MOST IMPORTANT QUESTIONS for Class 11 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter

NCERT MOST IMPORTANT QUESTIONS ON PLANT KINGDOM

Question 1.
How do red algae differ from brown algae?

Answer:
Differences between red algae and brown algae:

Red algae	Brown algae
1. Unicellular and microscopic only a few are filamentous and Heterotrichous.	1. Filaments and heterotrichous.
2. Phycoerythrin, phycocyanin and phycobilins pigments are present.	2. Fucoxanthin pigment is present.
3. Reserve food material is Floridian starch.	3. Reserve food material is Laminarian starch.
4. Chlorophyll ‘a’ present.	4. Chlorophyll ‘a’ + ‘c’ present.
5. e.g. Gelidium Polysiphonia.	5. e.g. Laminaria, Fucus and Surgaassum.

Red algae

Porphyra or Polysiphonia

Question 2.
Distinguish the reproductive organs of gymnosperms and angiosperms.

Answer:

Gymnosperms	Angiosperm
1. The sporophylls are aggregated to form cones.	1. The sporophylls are aggregated to produce flowers.
2. Microporosphyll consists of micro-sporangia bearing microspores.	2. Microsporophyll is differentiated into anther and filament.
3. Stigma and style are absent.	3. Stigma and style are present.
4. Ovule lies on the lower side and exposed to the megasporophyll.	4. Ovules are attached to the funic-ulus and are present inside the ovary.
5. One too many cotyledons are present.	5. One or two cotyledons are present.
6. Fruit formation doesn’t take place.	6. Fruit formation takes place.
7. Double fertilization is absent.	7. Double fertilization is present.
8. Archaegonia are present.	8. Archaegonia are present.

Question 3.
Mention the changes that take place when the fruit ripens.
Answer:

1. Starch is converted into sugar.
2. The production of various organic substances gives it a texture, taste and flavour.
3. The breakdown of chlorophyll leads to changes in the colour of the skin of the fruit.

Question 4.
Describe the important characteristics of gymnosperms.

Answer:
Characteristic features of gymnosperms:

1. Gymnosperms are evergreen woody, perennial plants.
2. Plants are heterosporous.
3. Reduction of gametophytic generation.
4. The enclosure of the female gametophyte by the megasporangium.
5. Ovules are exposed to receive pollen grains.
6. Gymnosperms possess exposed or naked seeds.
7. Polyembryony is a common occurrence.
8. Xylem lacks vessels and phloem lacks companion cells. Example Cycas, Pinus and Cedms.

Question 5.
Explain briefly the alternation of generation in bryophytes.

Answer:
Alternation of generations: Moss plants are a gametophyte. Spore is the beginning of the gametophytic generation. It develops into protonema which rises to male and female gametes produced in them. Club-shaped antheridium bears biflagellate sperms or antherozoids. Flask-shaped archegonium encloses the female egg. a zygote is formed after the fertilization (syngamy) of male and female gametes with the help of water

Repeated divisions of the zygote give rise to the embryo (2n) which soon develop into a sporophyte. The sporophyte of moss gets differentiated into three parts -foot, seta and capsule. Inside the capsule, single-celled spores are produced. After the dehiscences, they begin to germinate and give rise to the protonema to start the cycle again. Gametophytic generation alternates the sporophytic generation.

Question 6.
Draw the diplontic and haplo-diplontic cycles.
Answer:

Diplontic cycles

Haplo-diplontic cycles

Question 7.
What are angiosperms? Give their characteristic features.

Answer:
Angiosperms are a group of flowering plants where seeds are embedded in the fruits.

They show the following characters:

1. The ovules/seeds are enclosed within the ovary, or we may say that after fertilization seeds are located in the fruit.
2. Male and female gametes i.e. pollen grains and egg nucleus are borne by the flowers.
3. During pollination pollen grains fall on the stigma, they develop on the stigma of the ovary and male gametes enter the egg nucleus through Onicropyh.
4. Male gametophyte is a three-celled structure when dehisced.
5. Embryosac or female gametophyte is eight celled when young and becomes seven celled at the time of fertilization.
6. There is double fertilization wherein one male gamete fuses with the egg nucleus to form a diploid zygote and another fuse with the secondary nucleus to form a triploid endosperm.
7. Xylem consists of tracheids, vessels fibres and parenchyma while phloem consists of sieve tubes, companion cells and phloem parenchyma and fibres. Xylem conducts water to the tip of tall trees and phloem is responsible for the translocation of food.

Question 8.
Write brief notes on:

(i) Green algae
Answer:
Green Algae: The Class (Chlorophyta: ‘GK’ choros = green: phyton = plant) has over 7,000 species. They are in several shapes and sizes. Some are unicellular and microscopic. Some are motile colonies like Volvox. Some, are multinucleated but unicellular i.e. coenocytic like cholera.

Volvox

Chlamydomonas

Chara

(ii) Brown algae
Answer:
Brown Algae: The Class (Phaeophyta: GK: pharos = brown: phyton = plant) has about 2,000 species, mostly marine. Some of, the world’s largest sea plants measuring 40-60 metres long. Brown algae occur chiefly in cooler seas. Some are filamentous. Brown algae like Laminaria are attached firmly to the rocks below by holdfasts.

Laminaria

Fucus

Dictyota

(iii) Club moss
Answer:
Club mass: It belongs to Lycopsida. In most parts of the world, Lycopodium is found. Sporangia’ are produced on mature leaves.

(iv) Horsetail
Answer:
Horsetail: Also called Sphenopsida. This group exists only Equisetuin. Because they look like the tail of a horse, so they are called horsetail. These plants are up to 1 metre in length. But some extinct species are of several metres. The root, stem and leaves are true.

(v) Sporophyll
Answer:
SporphyMs: They are special spore-bearing leaves and. produce sporangia in sori on their underside, where haploid spores are formed by meiosis. Spores germinate to form an independent, small gametophyte, the prothallus. This bears archegonia and antheridia. Male gamete from antheridia and swim in a film of water to egg cells in archegonia and fertilize them.

Question 9.
Discuss the development of seed habit.

Answer:
The seed plants have two kinds of sporangia. These sporangia are born on the sporophylls.

One type of sporangia are ovule or megasparangium. The other type of sporangia is the pollen sac or archegonium. The egg develops a pollen sac or microsporangium. The egg develops in the ovule from the megaspores. Many pollen grains are produced in the pollen sac.

The pollen grains are dispersed by the air! They reach the ovule. The male gamete and the female egg cell fuse together. The zygote is formed as a result of fertilization. Later on, the zygote forms the embryo. The seed is developed from the ovule. The development of seed habit in gymnosperm and angiosperm do not require liquid water during fertilization

Question 10.
What are the different lifestyles shown by Angiosperms?
Answer:

1. Hydrophytic plants are the plants that live in water or swampy places. Hydrophytes are categorised into, two groups:
   (a) Submerged plants like Hydrilla, Vallisneria, Utriculria and
   (b) Floating plant-like Nymphea, Wolffia and Pistia.
2. Xerophytic plants are those plants that live in the scarcity of water e.g. cactus.
3. Halophytes are a type of xerophytic plants that are present in saline conditions.
4. Insectivorous plants-A few angiosperms, though green and autotrophic trap insects to overcome the shortage of nitrogen. For example, pitcher plant, sundew, bladderwort.

In This Post we are  providing Chapter-2 BIOLOGICAL CLASSIFICATION NCERT MOST IMPORTANT QUESTIONS for Class 11 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON BIOLOGICAL CLASSIFICATION

Question 1.
What are imperfect fungi?

Answer:
Asexually reproducing fungi belonging to Deuteromycites are imperfect fungi

Question 2.
How many basidiospores are formed after Karyogamy and meiosis?

Answer:4

Question 3.
What is plasmogamy?

Answer:
Fusion of protoplasms between two motile or non-motile gametes.

Question 4.
What are the slime molds?

Answer:
1. The slime molds are both plant and animal-like.

2. They are plant-like in the production of spores during reproduction and animal-like in the mode of nutrition and rheumatic organization.

3. Their rheumatic structure consists of an acellular, multinucleate mobile mass of protoplasm which lacks a good wall called plasmodium.

4. The reproductive stage consists of sporangia and spores formed after meiosis. The spores on germination produce either flagellated swarm cells or myxamoebae.

5. These divide mitotically, then behave as gametes and fuse in pairs to form a diploid zygote. The zygote nucleus divides mitotically but the nuclear division is not followed by cell wall formation so that all nuclei lie free in the cytoplasm.

6. The enlargement of the zygote into plasmodium takes place which moves freely on the substratum and feeds on bacteria, fungal and algal spores, and also absorbs nutrients directly from the substratum. The plas¬modium then settles on dry places and develops into sporangia. Therefore asexual stage is plant-like and the sexual stage is animal-like.

Question 5.
Write a short note on kingdom Plantae.

Kingdom Plantae

Answer:
1. Kingdom Plantae includes all autotrophic plants which are photosynthetic forms called green plants starting from simple algae, bryophytes, pteridophytes to gymnosperm and angiosperms.

2. The plant cell has a cell wall mainly made of cellulose and, eukaryotic structure with prominent chloroplasts. Some plants are heterophilic like insectivorous plants which feed on insects and flies e.g. Bladderwort and Venus flytrap.

(3) The life cycle has two phases-sporophytic and gametophytic which are diploid (2n) and haploid (n) respectively. That means zygote (2n) undergoes meiosis to form haploid (n) spores these spores germinate into a gametophyte, then these gametes (male and female) fuse to form a zygote (2n) again which gives rise to the sporophyte. This phenomenon is called the alternation of generation.

Question 6.
Write a short note on Mycoplasma.

Answer:

1. Discovered by E.Nocard and E.R. Roux (1998) mycoplasma is the smallest known aerobic prokaryotes without a cell wall.
2. They were isolated from cattle suffering from bovine pleuropneumonia and hence they were designated as PPLO (pleuropneumonia-like organisms)
3. They are found in different forms as a spheroid, thin, stellate called pleomorphic.
4. They occur in soil, sewage, human, and plants.

Question 7.
Write a short note on Kingdom Animalia.

Answer:

1. Kingdom Animalia includes all animals except the protozoan. The members are multicellular eukaryotes. The cell wall is absent cells, organized into tissue. They directly or indirectly depend on plants for food.
2. They digest their food in an internal cavity and store food reserves as glycogen or fat. They are heterotrophic and the mode of nutrition is holozoic nutrition. They act as decomposers and help in the recycling of minerals.
3. Kingdom Plantae includes the multicellular, photosynthetic eukaryotic forms.
4. They have well-established mechanisms for absorption and Kingdom Animalia includes all animals except the protozoans. They are multicellular eukaryotes and are holozoic. The cells lack walls.

Question 8.
Write a short note on Lichens.

Answer:
Lichens are a symbiotic association between algae and fungi. The algae component is known as phycobiont and the fungal component as mycobiont which are autotrophic and heterotrophic respectively. Algae prepare food for fungi and fungi provides shelter and absorbs mineral nutrient and water for its partner.

On the basis of the structure of thallus, lichens can be classified into three types

1. Crustose: forms a crust on the substrate which is not easily separated from the substrate e.g. Graphis
2. Foliose: forms the leafy lobed structure attached to the substrate with the help of rhizines easily separated from substrate eg. Parmelia.
3. Fruticose: forms shrubby, cylindrical, and branched thallus. They grow erect or hang from the substrate e.g. Usnea. Lichens are the pioneer colonizers of bare rocks. They also colonize tree trunks in temperate climatic regions.

Question 9.
Describe the kingdom Monera.

Answer:
This kingdom comprises single-celled prokaryotic organisms like bacteria, filamentous actinomycetes, and photosynthetic blue-green algae of Cyanobacteria. The salient features are already given in Table 2.1 we will further discuss the following organisms briefly.

Bacteria: Bacteria are single-celled microscope true prokaryotic organisms which are almost omnipresent. They colonize soil, water, and air. These can survive

in extreme environmental conditions like high temperature, high salt concentration, in absence of oxygen (anaerobic) or in presence of oxygen (aerobic) in high acidic or alkaline pH, etc. (sometimes these are called Archaebacteria).

Some bacteria can be chemotrophs that derive energy from inorganic compounds in absence of oxygen e.g. methanogenic bacteria produce methane gas (CH₄) from CO₂ and H₂, some live by oxidizing hydrogen supplied eg. Thiothsix.

Some are parasites on plants and animals e.g. Xanthomonas citri and Vibrio Cholera; another form symbiotic association with plant roots e.g. Rhizobium.

The bacteria can be of various sizes and shape i.e. spherical or round, coccus (pi. cocci), rod-shaped and bacillus (pi. Bacilli), spiral-shaped spirillum (pi. Priscilla). Long and helical shaped called spirochetes. Many bacteria have one or more slender, long flagellum (pi. flagella) which helps them to move in the liquid substrate. Some bacteria form endospores under poor nutrient conditions.

Question 10.
Write the distinct characters of protozoa.

Answer:
1. Protozoa are single-celled heterotrophs or ‘first animal’. They can be free-living and parasitic members, mobile with flagellar movement, by pseudopodia, or by ciliary movements e.g. Euglena and Amoeba.

2. Cell wall is absent in some like Amoeba so they can change their shape. The Euglena is autotrophic because of the presence of chlorophyll it performs photosynthesis but in the absence of light, it becomes heterotropic and ingests other protists or food particles.

3. They reproduce asexually by binary fission but some reproduce sexually by fusion of gametes followed by meiosis. Another important member of protists is the malarial parasite, Plasmodium, causing the notorious disease malaria in man, carried by mosquitoes, it multiplies rapidly in the liver of humans and brings about the cyclic fever releasing toxins into the bloodstream of its host.

Photograph of Amoeba and Euglenas

In This Post we are  providing Chapter-1 THE LIVING WORLD NCERT MOST IMPORTANT QUESTIONS for Class 11 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON THE LIVING WORLD

1. Why are living organisms classified?

Sol. Living organisms are classified because of the following reasons:
(i) Easy identification.
(ii)Study of organisms of other places.
(iii)Study of fossils
(iv)Grouping helps in study of all types of organisms while it is impossible to study individually all of them.
(v) Itbringsoutsimilaritiesanddissimilarities. They help in knowing relationships among different groups.
(vi)Evolution of various taxa can be known.

2. Why are the classification systems changing every now and then?

Sol. From very early days till now biologists use several characters for classification system. These are morphology, anatomy, cytology, physiology, ontogeny, phylogeny, reproduction, biochemistry, etc. But day by day biologists are learning something new about organisms from their fossil records and using” advanced study techniques such as molecular phylogeny, etc. So their point of view about classification keeps changing. Thus the system of classification is modified every now and then.

3. What different criteria would you choose to classify people that you meet often?

Sol. The various criteria that may be chosen to classify people whom we meet often include behaviour, geographical location, morphology, family members, relatives, friends etc.

4. What do we learn from identification of individuals and populations?

Sol. The knowledge of characteristic of an individual or its whole population helps in identification of similarities and dissimilarities among the individuals of same kind or between different types of organisms. It helps us to classify the organisms in various categories depending upon these similarities and dissimilarities.

5. Given below is the scientific name of mango. Identify the correctly written name.
Mangifera Indica Mangifera indica

Sol. The correctly written scientific name of mango is Mangifera indica.

6. Define a taxon. Give some example of taxa at different hierarchical levels.

Sol. A taxonomic unit in the biological system of classification of organism is called taxon (plural taxa). For example a phylum, order, family, genus or species represents taxon. It represents a rank. For example, all the insects form a taxon. Taxon of class category for birds is Aves and taxon of Phylum category for birds is Chordata. The degree of relationship and degree of similarity varies with the rank of the taxon. Individuals of a higher rank, say Order or Family, are less closely related than those of a lower rank, such as Genus or Species.

7. Can you identify the correct sequence of taxonomical categories?
(a) Species —> Order —> Phylum —> Kingdom
(b) Genus—) Species—> OrderKingdom
(c) Species —> Genus —>Order —> Phylum

Sol. The correct sequence of taxonomical categories is
(c) i.e., Species —>Genus —> Order —> Phylum.

8. Try to collect all the currently accepted meanings for the word ‘species’. Discuss with your teacher the meaning of species in case of higher plants and animals on one hand, and bacteria on the other hand.

Sol. Species occupies a key position in classification. It is the lowest taxonomic category. It is a natural population of individuals or group of populations which resemble one another in all essential morphological and reproductive characters so that they are able to interbreed freely and produce fertile offsprings. Each species is also called genetically distinct and reproductively isolated natural population. Mayr (1964) has defined species as “a group of actually or potentially interbreeding populations that are reproductively isolated from other such groups”.
In higher plants and animals the term ‘species’ refers to a group of individuals that are able to interbreed freely and produce fertile offsprings. But, in case of bacteria interbreeding cannot serve as the best criteria for delimiting species because bacteria usually reproduce asexually. Conjugation, transformation and transduction, which are termed as sexual reproduction methods in bacteria, also do not correspond to true interbreeding. Thus, for bacteria many other characters such as molecular homology, biochemical, physiological, ecological and morphological characters are taken into consideration while classifying them.

9. Define and understand the following terms:
(i) Phylum (ii) Class (iii) Family
(iv) Order (v) Genus

Sol. (i) Phylum – Phylum is a category higher than that of Class. The term Phylum is used for animals. A Phylum is formed of one or more classes, e.g., the Phylum Chordata of animals contains not only the class Mammalia but also Aves (birds), Reptilia (reptiles), Amphibia (amphibians), etc. In plants the term Division is used in place of Phylum.
(ii) Class – A Class is made of one or more related Orders. For example, the Class Dicotyledoneae of flowering plants contains all dicots which are grouped into several orders (e.g., Rosales, Sapindales, Ranales, etc.).
(iii) Family, – It is a taxonomic category which contains one or more related genera. All the genera of a family have some common features or correlated characters. They are separable from genera of a related family by important and characteristic differences in both vegetative and reproductive features. E.g., the genera of cats (Fells) and leopard (Panthera) are included in the Family Felidae. The members of Family Felidae are quite distinct from those of Family Canidae (dogs, foxes, wolves).
Similarly, the family Solanaceae contains a number of genera like Solanum, Datura, Petunia and Nicotiana. They are distinguishable from the genera of the related family Convolvulaceae (Convolvulus, Ipomoea).
(iv) Order – The category includes one or more related families. E.g., the plant Family Solanaceae is placed in the Order Polemoniales alongwith four other related families (Convolvulaceae, Boraginaceae, Hydrophyllaceae and Polemoniaceae). Similarly, the animal families Felidae and Canidae are included under the Order Carnivora alongwith Hyaenidae (hyaenas) and Ursidae (bears).
(v) Genus – It is a group or assemblage of related species which resemble one another in certain correlated characters. Correlated characters are those similar or common features which are used in delimitation of a taxon above the rank of species. All the species of genus are presumed to have evolved from a common ancestor. A genus may have a single living species e.g., Genus Homo. Its species is Homo sapiens – the living or modem man. The Genus Felis has many species, e.g., F. domestica – common cat, F. chaus (jungle cat) etc.

10.How is a key helpful in the identification and classification of an organism?

Sol.‘Key is an artificial analytic device having a list of statements with dichotomic table of alternate characteristics. Taxonomic
keys are aids for rapid identification of unknown plants and animals based on
the similarities and dissimilarities. Keys are primarily based on stable and reliable characters. The keys are helpful in a faster preliminary identification which can be backed up by confirmation through comparison with detailed description of the taxon provisionally identified with. Separate taxonomic keys are used for each taxonomic category like Family, Genus and Species.

In This Post we are  providing Chapter-7 ENVIRONMENTAL CHEMISTRY NCERT MOST IMPORTANT QUESTIONS for Class 11 CHEMISTRY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON ENVIRONMENTAL CHEMISTRY

1.What is troposphere?

Ans:The lowest region atmosphere in which the human beings along with other organisms live is called troposphere. It extends upto the height of km from sea level.

---

2.Name some gaseous air pollutants.

Ans:Gaseous air pollutants are oxides of sulphur, nitrogen and carbon, hydrogen sulphide, hydrocarbons, ozone and other oxidants.

---

3.What are the diseases caused by sulphur dioxide?

Ans:Sulphur dioxide causes respiratory diseases eg. asthma, bronchitis, emphysema in human beings, sulphur dioxide causes irritation to the eyes, resulting in tears and redness.

---

4.List gases which are responsible for green house effect?

Ans:Carbon dioxide, methane, water vapors, nitrous oxide, CFC’s and ozone are responsible for green house effect.

---

5.What is the effect of CFC’s on ozone layer?

Ans: 02Chlorofluorocarbon (CFC’s) damage the ozone layer and creates holes in ozone layer.

---

6.What is greenhouse effect?

Ans:Atmosphere traps the Sun’s heat near the Earth’s surface and keeps it warm. This is Greenhouse effect.

---

7.Which disease is caused due to ozone layer depletion?

Ans:Ultraviolet rays reaching the earth passing through the ozone hole cause skin cancer.

---

8.What is smog?

Ans: When smoke with fog, it is called smog.

---

9.The London smog is caused in which season and time of the day?

Ans: The London smog is caused during summer season and in the afternoon part of the day when it is very hot.

---

10.Name two gases which form acid rain.

Ans: 04SO₂ and NO₂.

---

11.Which acid is present is the acid rain?

Ans: 05The acids present in the acid rain are

H₂SO₄, HNO₃ and HCl.

---

12.What is PAN?

Ans: 06PAN is Peroxy acetyl nitrate.

---

13.When does rain water become acid rain?

Ans: 08When pH of rain water becomes as low as 2 to 3.5. It forms acid rain.

---

14.What is BOD?

Ans: 01BOD stands for Biochemical Oxygen Demand.

---

15.Define green chemistry.

Ans: 03The branch of chemistry that emphasizes on the processes and products that reduce or eliminate the use and generation of toxic / hazardous substances is called green chemistry.

---

---

---

---

---

In This Post we are  providing Chapter-6 HYDROCARBONS NCERT MOST IMPORTANT QUESTIONS for Class 11 CHEMISTRY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON HYDROCARBONS

Question 1.
The following organic compounds are known by their common names

(i) Neopentane
Answer:
Neopentane is

& its h.U.P.A.C. name is 2, 2—dimethyl propane.

(ii) Acetone
Answer:
Acetone is

and its I.U.P.A.C. name is Propanone.

(iii) Vinyl chloride
Answer:
Vinyl chloride is CPU = CH — Cl and its I.U.P.A.C. name are chloroethene.

(iv) Tert butyl alcohol. Write their structural formulae and I.U.P.A.C. names.
Answer:
Tert; butyl alcohol

and its I.U.P.A.C. name is 2-methyl propan-2-ol.

Question 2.
What are the various products expected when propane reacts with fuming nitric acid?

Answer:

Question 3.
How will you convert methane into
(i) Methanol

Answer:
Conversion of methane into methanol:

(ii) Methanal.

Answer:

Question 4.
What is aromatization? How will you convert ^hexane into benzene?

Answer:
Aromatization. It is the process that involves cyclization, isomerization, and dehydrogenation with the application of heat and catalyst to convert alkanes containing six or more carbon atoms into aromatic hydrocarbons.

Question 5.
Give the different conformations of ethane with their
(i) Sawhorse representation and
(ii) Newmann Projection formulae.

Answer:
Sawhorse representation Newmann projection models

Question 6.
What are the relative stabilities of different conformations of ethane? Is it possible to isolate these at room temperature?

Answer:
The staggering form of ethane is more stable than the eclipsed form because the force of repulsion between hydrogen atoms on adjacent C atoms is minimum. The energy difference between the staggered form and eclipsed form of ethane is just 12.55 kJ mol^-1. Therefore, it is not possible to separate these two forms of ethane at room temperature.

Question 7.
What is Saytzeff Rule? What are the expected products when 2-Bromobutane is dehydrohalogenation with ale. KOH?

Answer:
Saytzeff Rule. Whatever two alkenes are theoretically possible during a dehydrohalogenation reaction, it is always the more highly substituted alkene that predominates.

Question 8.
What is the order of reactivity of H₂C = CH₂, (CH₃)₂, H₂C = CH₂, CH₃ – CH = CH₂, CH₃ – CH = CH – CH₃, (CH₃)₂ C = C (CH₃)₂, (CH₃)₂ C = CH CH₃ towards electrophilic addition reactions?

Answer:
The order of reactivity of the above alkenes towards electrophilic addition reactions decreases in the order.
(CH₃)₂ C = C (CH₃)₂ > (CH₃3)₂ C = CH CH₃ > (CH₃)₂ C = CH₂ > CH₃ CH – CH – CH₃ > CH₃ – CH = CH, > CH₂ = CH₂.

Question 9.
Define Markownikov rule. Explain it with an example.

Answer:
Markownikov rule states. The negative part of the addendum adding to an unsymmetric alkene goes to that C atom of the double bond which is attached to a lesser number of C atoms.

Question 10.
What is the Peroxide effect/Kharasch Effect? Illustrate with an example.

Answer:
In the presence of peroxides such as benzoyl peroxide, the addition of HBr (but not of HCl or HI) to an unsymmetrical alkene takes place contrary to the Markownikov rule. This is known as the peroxide/Kharsch effect.

In This Post we are  providing Chapter-5 ORGANIC CHEMISTRY: SOME BASIC PRINCIPLE AND TECHNIQUE NCERT MOST IMPORTANT QUESTIONS for Class 11 CHEMISTRY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON ORGANIC CHEMISTRY: SOME BASIC PRINCIPLE AND TECHNIQUE

Question 1.
Without using column chromatography, how will you separate a mixture of camphor and benzoic acid?

Answer:
Sublimation cannot be used as both camphor and benzoic acid sublime on heating. Therefore, a chemical method using NaHCO₃ solution is used when benzoic acid dissolves leaving camphor behind. The filtrate is then cooled with dilute HCl to get benzoic acid.

Question 2.
Compare inductive & mesomeric effects.

Answer:

Inductive effect	Mesomeric effect
1. It operates in saturated gp. of compounds.	1. It occurs in unsaturated & especially in conjugated compounds.
2. It involves electrons in σ – bonds.	2. It involves electrons in π – bonds.
3. Electron pair is slightly displaced & there only partial charges are developed.	3. The electron pair is transferred completely with the result full positive & negative charges are created.
4. It is transmitted over only a quite short distance.	4. It is transmitted from one end to the other of quite large molecules provided conjugation (i.e. delocalised orbitals) is present through which it can proceed.

Question 3.
What is the difference between distillation, distillation under reduced pressure & steam distillation?

Answer:

Distillation	Distillation under reduced pressure	Steam distillation
This is used to separate volatile liquid from non-volatile liquid or solid separately.	This is used to purify liquids that decompose at or below their boiling points.	This is used for purifying substances that are steam volatile & immiscible with water.

Question 4.
How will you purify sugar which has impurities of sodium chloride?

Answer:
Sugar may be purified by the crystallization method. This can be purified by shaking the impure solid with hot ethanol at 345K. The sugar will dissolve whereas common salt remains insoluble. The hot solution is filtered, concentrated & allowed to cool when crystals of sugar will separate out. In this case, hot water has been used as a solvent. The purification of sugar would not have been possible since both sugar’& common salt are soluble in water.

Question 5.
Differentiate between Ionic & free radical reactions.

Answer:

Ionic reactions	Free radical reactions
1. These occur only rarely in the gas phase but mainly in a solution of polar solvents; the reaction is influenced by the polarity of the solvent.	1. These occur in gas phases or in non-polar solvents.

Question 6.
For each of the following compounds, write a more condensed formula & also their bond-line formula.

(b) HOCH2CH2CH2CHCH3CHCH3CH3

Answer:

Question 7.
Expand each of the following bond line formulae to show all the atoms including carbon & hydrogen.

Answer:

Answer:

Answer:

Question 8.
Explain why is (CH₃) C+ more stable than CH₃ C⁺ H₂ & C⁺ H₃ is the least stable cation?

Answer:
Hyperconjugation interaction in (CH₃)₃ C⁺ is greater than in C+⁺ H₃ C⁺ H₂ has 9 C -H bonds. In C H₃, the C -H bonds are in the nodal plane of the vacant 2p-orbital & hence cannot overlap with it.
Thus C⁺ H₃ is least stable.

Question 7.
The choice of the solvent is of great importance in crystallizing organic substances. What are the characteristics of a suitable solvent?

Answer:
A suitable solvent must have the following characteristics;

1. The impurities & pure compound must have a large difference in their solubilities.
2. The pure compound must have low solubility at room temperature but high solubility at its boiling point.
3. The impurity should either be insoluble at room temperature or must have high solubility so that crystallization may give a high yield.
4. The solvent should have an average boiling point.
5. The solvent should neither react with the compound nor with impurities.
6. The solvent should not be highly inflammable.

Question 8.
Explain the principle of steam distillation.

Answer:
Steam distillation: The process of steam distillation is employed in the purification of substance from non-volatile impurities provided the substance itself is volatile in steam and insoluble in water.

This method is based on the facts that

1. A liquid boils at a temperature when its vapour pressure becomes equal to the atmospheric pressure.
2. The vapour pressure of a mixture of two immiscible liquids is equal to the sum of the vapour pressures of the individual liquids.

In the actual process, steam is continuously passed through the impure organic liquid. Steam heats the liquid and it gets practically condensed to water. After some time mixture of the liquid and water begins to boil, because the vapour pressure of the mixture becomes equal to the atmospheric pressure.

Obviously, this happens at a temperature that is lower than the boiling point of the substance or that of water. Thus an organic compound boils below its boiling points and chances of decomposition avoided. For example, a mixture of aniline (b.p 453 K) with decomposition and water (b.p. 373 K) under normal atmospheric pressure boils at 371K. At this temperature the

Steam Distillation

water boils at 371 K. At this temperature, the vapour pressure of water is 717 mm and that of aniline is 43 mm and therefore the total pressure is equal, to 760 mm. Thus in steam distillation, the liquid gets distilled at a temperature lower than its boiling point and chances of decomposition avoided. The proportion of water and liquid in the mixture that distils over is given by the relation.

w1w2=P1×18P2×M
where w₁ and w₂ stand for the masses of water and liquid that distils over. P₁ and P₂ are vapour pressure of water and of liquid at the distillation temperature and M is the molecular mass of the liquid.

Question 9.
Dehydrobromination of compounds (A) and (B) yield the same alkene (c) Alkene (c) Can regenerate (A) and (B) by the addition of HBr in the presence and absence of peroxide respectively. Hydrolysis of A and B give isomeric products (D) and (E) respectively. 1, 1-Diphenyl ethane is obtained on the reaction of (C) of benzene in the presence of H⁺ ions. Give structures of A to E with reactions.

Answer:
Alkene (C) on reaction with benzene in the presence of H+ ions gives 1, 1-Diphenyl ethane. Therefore C must be styrene as depicted below

Now dehydrobromination of A and B give the same alkene C, i.e.,
styrene.
∴ A and B must be isomeric alkyl bromide.

A and B can be obtained by the addition of HBr in the presence and absence of peroxide to styrene.

Hydrolysis of A and B give isomeric alcohols (D) & (E) as

Question 10.
What are reaction intermediates? How are they generated by bond fission?

Answer:
The species which are generated as a result of bond fission are called reaction intermediates. The important reaction intermediates are:
1. Free Radicals: A free radical may be defined as an atom or group of atoms having an impaired electron. These are obtained as a result of homolytic fission of covalent bonds.

These free radicals are neutral particles, extremely transient, (short-lived) and highly reactive. They get consumed as soon as they are formed. They pair up their electron with another electron from wherever it is available. They occur only as a reaction intermediate. Their presence is felt in reactions, but cannot be isolated in a free state. For example dissociation of Cl2 gas in the presence of Ultraviolet light produces free radicals.

The alkyl free radicals are obtained when free radical: Cl reacts with alkanes.

Free radical may be primary, secondary, tertiary depending upon whether, one, two or three carbon atom attached to the carbon atoms carrying the odd electron.

The stability is CH₃ < 1° < 2° < 3°.

2. Carbocation or carbonium ion: It is defined as a group of atoms that contain positively charged carbon having only six electrons. It is obtained by heterolytic fission of a covalent bond involving a carbon atom.

They are also classified as primary, secondary and tertiary depending upon whether one, two or three carbon atoms are attached to the carbon bearing the positive charge as:

Thus the order of stability if CH₃⁺ < 1° < 2° < 3°.

3. Carbanion: A carbanion may be defined as a species containing a carbon atom carrying a negative charge. These are generated by the atom in which the atom linked to carbon goes without the bonding electrons. As a result of this carbon acquires a negative charge. For example, the removal of hydrogen of methyl part of acetaldehyde molecule as H+ ion leaving both the electron on carbon.

They are also very reactive species. They are also classified as primary, secondary and tertiary depending upon whether one, two or three carbon atoms are attached to the carbon atom bearing negative
charge.

The order of stability is the reverse of free radicals and carbocations
CH₃ ^– > 1° > 2° > 3°.

(iv) Carbenes: The carbenes are reactive neutral species in which carbon atom has six electrons in the valency shell out of which two are shared. The simplest carbene is methylene (CH₂). It is formed when diazomethane is decomposed by the action of light.

It is very reactive. It reacts with alkenes by adding to the double bond forming cyclopropane.