Category: Class 11 Biology Objective Questions

250+ TOP MCQs on Chemical Control and Coordination – Human Endocrine System and Answers

Biology Exam Questions for AIIMS Exam on “Chemical Control and Coordination – Human Endocrine System”.

1. Which hormone is responsible for reabsorption of sodium ions and water?
a) Adrenaline
b) Glucocorticoids
c) Testosterone
d) Aldosterone

Answer: d
Clarification: Aldosterone is the main mineralocorticoid in our body. It is mainly responsible for fluid regulation in the body and hence propagates reabsorption of sodium ions and excretion of phosphate ions.

2. Which of these hormones generates lipolysis and proteolysis and also inhibits cellular uptake?
a) Insulin
b) Aldosterone
c) Glucocorticoid
d) Glucagon

Answer: c
Clarification: Glucocorticoids are responsible for carbohydrate metabolism in our body. It is responsible for gluconeogenesis, lipolysis and proteolysis. It inhibits cellular uptake of available nutrients.

3. Which hormone is responsible for regulating the osmotic pressure and body fluid volume?
a) Oxytocin
b) Prolactin
c) Aldosterone
d) Glucocorticoids

Answer: c
Clarification: The adrenal cortex mainly secretes hormones commonly known as corticoids. Aldosterone is the main mineralocorticoid in the body responsible for regulating osmotic pressure and body fluid levels.

4. Which type of cells of the Islet of Langerhans are responsible for hyperglycemia?
a) β-cells
b) α-cells
c) δ-cells
d) F cells

Answer: a
Clarification: Islet of Langerhans consists of two major types of cells, namely, α-cells and β-cells. β-cells are responsible for the secretion of insulin, which is responsible for hyperglycaemia or high blood sugar.

5. Corpus luteum is responsible for the secretion of which hormone?
a) Estrogen
b) Progesterone
c) Vasopressin
d) Melatonin

Answer: b
Clarification: Ovaries produce two groups of steroid hormones known as estrogen and progesterone. After ovulation, the ruptured follicle is converted into a structure known as corpus luteum, which is responsible for progesterone secretion.

6. Which of these supports pregnancy and stimulates milk secretion?
a) Corpus luteum
b) Ovum
c) Progesterone
d) Estrogen

Answer: c
Clarification: Ovaries release two steroid hormones known as estrogen and progesterone which are a part of female reproductive system. Progesterone helps with the formation of alveoli and the process of secretion of milk.

7. Leydig cells are responsible for the production of ______
a) testosterone
b) estrogen
c) progesterone
d) erythropoietin

Answer: a
Clarification: Testis is composed of seminiferous tubules and Leydig cells or interstitial cells. The Leydig cells are responsible for the production of androgens, especially testosterone which is the male sex hormone.

8. Which disorder involves the formation of ketone bodies?
a) Graves’ disease
b) Diabetes insipidus
c) Acromegaly
d) Diabetes mellitus

Answer: d
Clarification: Prolonged hyperglycemia leads to a disorder called diabetes mellitus. It is characterized by weight loss, frequent urination, presence of glucose in urine or glycosuria and the formation of ketone bodies.

9. Which gland is both endocrine and exocrine?
a) Thyroid gland
b) Adrenal gland
c) Pancreas
d) Parathyroid gland

Answer: c
Clarification: Many glands in the endocrine system can perform more than one function. Pancreas is a composite gland that acts as both an endocrine and an exocrine gland. The Islets of Langerhans cells are mainly endocrine.

10. The stromal tissue of the testis is responsible for the production of testosterone. True or false?
a) True
b) False

Answer: a
Clarification: Testis is composed of seminiferous tubules and stromal or interstitial tissue. The stromal tissue which is composed of Leydig cells is responsible for the production of androgens, mainly testosterone.

11. The α-cells in the pancreas secrete which hormone?
a) Somatotropin
b) Somatostatin
c) Insulin
d) Glucagon

Answer: d
Clarification: The Islets of Langerhans in the pancreas contain mostly α-cells and β-cells. The α-cells are responsible for the secretion of glucagon while the latter is responsible for the secretion of insulin.

12. Which of these hormones stimulates glycogenesis?
a) Glucagon
b) Erythropoietin
c) Insulin
d) Secretin

Answer: c
Clarification: Insulin stimulates the conversion of glucose to glycogen, which is stored in the liver and muscles, via a process known as glycogenesis. Thus, insulin helps maintain homeostasis by regulating the blood sugar level.

13. Which of these is not a steroid hormone?
a) Estrogen
b) Progesterone
c) Vasopressin
d) Triiodothyronine

Answer: c
Clarification: Vasopressin is a protein hormone. It is a nonapeptide. Triiodothyronine is secreted by thyroid gland while estrogen and progesterone are steroid hormones that are secreted by the ovaries.

250+ TOP MCQs on Living and Non Living and Answers

Biology Quiz for Class 11 on “Living and Non Living – 2”.

1. Increase in mass and increase in number are twin characteristics of growth.
a) True
b) False
Answer: a
Clarification: Multicellular organisms grow by cell division, i.e. increase in number which thereby leads to increase in mass.

2. Which organism among the following reproduce?
a) Mules
b) Worker bees
c) Fertile human couple
d) Infertile human couple
Answer: c
Clarification: Fertile human couple successfully produces offspring but mules, worker bees and an infertile human couple are incapable of reproduction.

3. The sum total of all the chemical reactions occurring in our body known as ______
a) Anabolism
b) Metabolism
c) Amphibolism
d) Catabolism
Answer: b
Clarification: Metabolism is the total set of life-sustaining chemical reactions in organisms. Anabolism is a set of constructive processes. Catabolism is a set of destructive processes. Amphibolism leads to both constructive and destructive outcomes.

4. Living and non-living organisms can be differentiated unexceptionally on the basis of _________
a) Growth
b) Consciousness
c) Metabolism
d) Reproduction
Answer: d
Clarification: Reproduction is the only criteria by which living and non-living organisms can be differentiated without any exception. Growth is seen in non-living organisms as well. Metabolism can be carried out in-vitro. Consciousness is also present in patients in coma.

5. Pick the man-made non-living thing.
a) Mountains
b) Valleys
c) Books
d) Rivers
Answer: c
Clarification: Books are non-living and also manmade whereas mountains, rivers and valleys are non- living but occur naturally.

6. A student wanted to keep a pet rat. He kept it inside a closed cage and found that the rat died the next day. Select the reason behind the death of the rat.
a) It did not get the space to move
b) It did not get sunlight to grow
c) It did not get air to breathe
d) It did not get food to eat
Answer: c
Clarification: The rat couldn’t survive because of the lack of air to breathe. A rat can live without space to move, sunlight and food for a few days.

7. Statement A: Natural things can be living or non-living.
Statement B: Living things can be natural.
a) Both the statements are true
b) Both the statements are false
c) Statement A is true but Statement B is false
d) Statement B is true but Statement A is false
Answer: a
Clarification: Both the statements are correct. Natural things are both living and non-living but Living things are always made by nature.

8. Sun is essential for plants as it provides _____
a) Water
b) Roots
c) Food
d) Energy
Answer: d
Clarification: Sun provides energy to plants. Water has to provided to plants or they obtain it naturally from rain. Roots are a part of the plant body which helps in obtaining food, water and minerals. Plants make their own food.

9. Budding is observed in _____
a) Planaria
b) Amoeba
c) Yeast
d) Protonema of mosses
Answer: c
Clarification: Budding is a method of asexual reproduction observed in lower organisms. Yeast multiply through budding. Planaria, Amoeba and Protonema of mosses multiply respectively through regeneration, binary fission and fragmentation respectively.

10. Growth and reproduction are mutually exclusive events in case of the majority of plants and animals.
a) True
b) False
Answer: a
Clarification: Growth is an increase in mass from inside or outside or both whereas reproduction refers to the production of progenies. Growth takes place in both living and non-living organisms but reproduction is seen only in living beings.

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250+ TOP MCQs on Classification in Plantae and Answers

Biology Multiple Choice Questions on “Classification in Plantae”.

1. Blue-green algae belong to the phylum of algae.
a) True
b) False
Answer: b
Clarification: Blue green algae or cyano-bacteria belong to the kingdom of Monera and falls under the category of Eubacteria. Earlier it was thought to be a part of algae.

2. Plantae doesn’t consist of mushrooms.
a) True
b) False
Answer: a
Clarification: Mushroom, few other fungi and blue-green algae which were earlier considered to be plants are now put under different kingdoms. Mushrooms belong to the kingdom fungi and blue-green algae or cyanobacteria are classified under Monera.

3. What is the major difference between plant cell and an animal cell?
a) Cell wall
b) Cell membrane
c) Eukaryotic nature of cells
d) Genetic material
Answer: a
Clarification: Plant cells contain an extra layer outside their cell membrane called cell wall. Cell wall plays a major role in the metabolic activities of a plant cell. It helps in controlling of osmotic pressure.

4. Artificial classification of plant kingdom is based on _______
a) Morphological characteristics
b) Embryotic structure
c) Ultra structure
d) Filamentous structure
Answer: a
Clarification: Artificial classification is based on morphological structures of the plant i.e. artificial classification on external structure of the plants than their internal structure.

5. Which among the following is incorrect about artificial classification of plantae kingdom?
a) This classification is mainly based on external features of a plant than that of their internal features
b) It laid the concept of classification in plants
c) Sexual organs are given more preference than vegetative organs
d) Artificial classification classifies closely related species
Answer: c
Clarification: Artificial classification is the oldest mode of classification in plantae kingdom. This classification laid the foundation for classification in plants. Artificial classification classifies closely related species under one category. However, in this mode of classification vegetative and sexual characteristics are given equal preference.

6. The mode of classifying plants as shrubs, herbs and trees comes under ________
a) Artificial classification
b) Natural classification
c) Phylogenetic classification
d) Whittaker’s classification
Answer: a
Clarification: The mode of classifying plants as shrubs, herbs and trees come under artificial classification. In this mode of classification, morphological characteristics of plants are considered to be the basis of classification.

7. Which among the following are incorrect about natural classification?
a) In natural classification, only internal structures of the plants are considered
b) Natural classification overcomes the limitations of the artificial classification
c) Natural classification considers reproductive mode, embryotic structure and ultra structure of plants
d) Natural classification establishes close relationship between plants
Answer: a
Clarification: Natural classification overcomes the limitations of the plants. Both internal and external structures are considered to be the basis of natural classification. Natural classification considers reproductive mode, embryotic structure and ultra structure of plants. It establishes close relationship between plants.

8. Phylogenetic classification considers __________
a) Morphological characteristics
b) Embryotic structure
c) Evolutionary relationships
d) Ultra structure
Answer: c
Clarification: Phylogenetic classification considers evolutionary relationships between organisms. Fossil records, cytotaxonomy, chemotaxonomy and numerical taxonomy help in studying their evolutionary structures.

9. Which among the following is incorrect about numerical taxonomy?
a) Numerical classification is based on mathematical calculations based on observable characteristics
b) Numbers are given to each character
c) The more the number of similar characters, the more is the chance that they belong to similar taxa
d) Numerical taxonomy gives the same result irrespective of the different sets of characteristics considered
Answer: d
Clarification: Numerical classification is based on mathematical calculations based on observable characteristics. In this mode of classification, each character is given a number or a code. The more the number of similar characters, the more is the chance that they belong to similar taxon. The main disadvantage of numerical taxonomy comes with the variation in result with variation in set of characteristics.

10. Which among the following is incorrect about cytotaxonomy and chemotaxonomy?
a) Cytotaxonomy is based on the chromosomes present in the organism
b) Chemotaxonomy is based on the chemical composition of plants
c) Cytotaxonomy involves characteristics like number of chromosomes, division of cell and position centromere
d) Cytotaxonomy involves only external characteristics
Answer: d
Clarification: Cytotaxonomy is based on the chromosomes present in the organism. Cytotaxonomy involves both internal and external characteristics of plant. Cytotaxonomy involves characteristics like number of chromosomes, division of cell and position centromere. Chemotaxonomy is based on the chemical composition of plants.

250+ TOP MCQs on Animal Kingdom – Chordata-1 and Answers

Biology Multiple Choice Questions on “Animal Kingdom – Chordata-1”.

1. Which among the following is incorrect about chordates?
a) They must have notochord at every point of their life
b) They have a post anal tail
c) They have hollow dorsal nerve cord
d) They have a ventral heart
Answer: a
Clarification: In chordates, notochord at some point of their life and may vanish after certain period of time. They have a post anal tail. They have a dorsal nerve cord. They have a ventral heart.

2. Which among the following is incorrect about chordata?
a) They have paired muscles
b) Post anal tail must be present in chordates
c) Their notochord vanishes after certain period of time
d) Pharyngeal gill slits are present
Answer: b
Clarification: Chordates have paired muscles. Post anal tail is present at the embryo but might vanish after certain period of time. Their notochord also vanishes after certain period of time. Pharyngeal gill slits are present.

3. Which among the following is odd?
a) Urochordata
b) Cephalochordata
c) Vertebrata
d) Agnatha
Answer: d
Clarification: Urochordata, Cephalochordata and Vertebrata are sub-phyla of Chordata. These sub-phyla are classified based on the period of presence of notochord in Chordates. Whereas unlike other three options, Agnatha is a super class in Chordates.

4. Which among the following is not correct about Urochordata?
a) They are a classification under Protochordates
b) They have post anal tail only till their larval stage
c) Most of these are marine and almost extinct
d) They don’t contain gill clefts
Answer: d
Clarification: Urochordata is classified under Protochordates. They have post anal tail only till their larval stage. Most of these are marine and almost extinct. They contain pharyngeal gill slits in the form of gill clefts.

5. Branchiostoma is an example of Cephalochordata.
a) True
b) False
Answer: a
Clarification: Ascidia, Salpa, Doliolum etc. are examples of Urochordata. Branchiostoma which resembles like finless fish is actually an example of Cephalochordata. The Cephalochordates and Urochordates are grouped under Protochordates.

6. Which among the following is incorrect about Vertebrata?
a) All chordates are vertebrates
b) In vertebrates, notochord is replaced by vertebral column in adults
c) They might not have post-anal tail after a certain period of time
d) Notochord is present during embryonic period
Answer: a
Clarification: All vertebrates are chordates but the vice-versa is not true. Notochord is present during embryonic period. It is replaced by vertebral column in adults. They might also not have post-anal tail after a certain period of time.

7. Agnatha is an example of ________
a) Sub-phylum
b) Phylum
c) Super-class
d) Class
Answer: c
Clarification: Super-class is a taxonomic category that is just above the class and below sub-phylum. Animal kingdom is divided into 10 phyla and one among them is Chordates. Chordates are further classified into two sub-phylum, namely, protochordates and vertebrata. Vertebrata are further classified into super classes, namely, agnatha and gnathostomata.

8. Which among the following is incorrect about Agnatha?
a) These are also called as jawless fishes
b) Scales and fins are present
c) They adopt parasitic mode of nutrition
d) They have a circular mouth that acts as sucker
Answer: b
Clarification: Agnatha are also called as jawless fishes. Scales and fins are absent. They adopt parasitic mode of nutrition. Their circular mouth acts as sucker. They are aquatic and most of them are extinct. The only class that exists in this super-class is cyclostomata.

9. Which among the following is incorrect about Cyclostomata?
a) Their vertebral column is made of cartilage
b) Lamprey and hagfish are examples of this class
c) Their digestive system is complete with stomach, food pipe and intestines
d) Their circulatory system is closed with a 2 chambered heart
Answer: c
Clarification: Vertebral column is made of cartilage in Cyclostomata. They don’t have a stomach. Their circulatory system is closed with a 2 chambered heart. Lamprey and hagfish are examples of this class.

10. Which among the following is incorrect about Gnathostomata?
a) These are vertebrates with jaws
b) This super class is classified into Pisces and tetrapods based on their type of blood
c) Pisces use fins for their movement
d) Tetrapods use limbs for their movement
Answer: b
Clarification: Gnathostomata are vertebrates with jaws. This super class is classified into psices and tetrapods based on the organs they use for their movement. Pisces use fins for their movement. Tetrapods use limbs for their movement.

250+ TOP MCQs on Animal Tissues-2 and Answers

Zoology Exam Questions and Answers on “Animal Tissues-2”.

1. The classification of glands is based on which of the following?
a) Mode of differentiation
b) Mode of pouring of secretions
c) Mode of cellular division
d) Number of cells
Answer: b
Clarification: Glands are of mainly two types- exocrine and endocrine glands. These glands are divided on the basis of mode of pouring of their secretions. For example, if secretions are poured through the ducts then these are called exocrine glands and if secretions are poured directly into the blood then they are called endocrine glands.

2. Some of the squamous epithelial cells get specialised for the secretion and are called the glandular epithelium.
a) True
b) False
Answer: b
Clarification: Some of the columnar or cuboidal cells get specialised for the secretion and are called as glandular epithelium. They are mainly of two types- unicellular glands and multicellular glands.

3. Which of the following structures does the given figure represent?

a) Multicellular gland
b) Endocrine gland
c) Exocrine gland
d) Unicellular gland
Answer: d
Clarification: The given diagram represents unicellular gland. The unicellular gland consists of isolated glandular cells, for example, goblet cells of the alimentary canal which secrete mucus.

4. Which of the following structures does the given figure represent?

a) Multicellular gland
b) Compound epithelium
c) Squamous epithelium
d) Unicellular gland
Answer: a
Clarification: The given diagram represents a multicellular gland. It consists of a cluster of cells, for example, the salivary gland. Most of the glands present in our body are multicellular glands.

5. Which of the following is not a secretion of exocrine glands?
a) Mucus
b) Saliva
c) Hormones
d) Ear wax
Answer: c
Clarification: Exocrine gland secretes mucus, saliva, earwax, oil, milk, digestive enzymes and other cell products. Their products are released through ducts or tubes. In contrast, endocrine glands do not have ducts. Their products are called hormones and are secreted directly into the fluid bathing the gland.

6. Which of the following is an incorrect statement regarding compound epithelium?
a) The main function is secretion and absorption
b) Cover dry surface of the skin
c) Made of more than one layer of cells
d) Cover moist surface of the buccal cavity
Answer: a
Clarification: Compound epithelium is made up of more than one layer of cells and thus has a limited role in secretion and absorption. Their main function is to protect against chemical and mechanical stresses. They cover the dry surface of the skin and also the moist surface of the buccal cavity.

7. Which of the following junctions help to stop substances from leaking against a tissue?
a) Adhering junctions
b) Gap junctions
c) Tight junctions
d) Loose junctions
Answer: c
Clarification: In nearly all the animal tissues, specialised junctions provide both structural and functional links between its cells. Tight junctions help to stop substances from leaking across a tissue.

8. Which of the following is the most abundant and widely distributed tissue in the human body?
a) Muscular tissue
b) Connective tissue
c) Epithelial tissue
d) Neural tissue
Answer: b
Clarification: Connective tissues are the most abundant and widely distributed tissues in the body of complex animals. They are named connective tissues because of their special function of linking and supporting other tissues or organs of the body.

9. Which of the following is not a type of connective tissue?
a) Loose
b) Dense
c) Specialised
d) Smooth
Answer: d
Clarification: Connective tissues are classified into three types-
i. Loose connective tissue
ii. Dense connective tissue
iii. Specialised connective tissue
In all the connective tissues except blood, the cells secret fibres of structural proteins called collagen or elastin.

10. Which of the following is not a function of fibres of connective tissue?
a) Strength
b) Elasticity
c) Flexibility
d) Longevity
Answer: d
Clarification: The fibres of connective tissue provide strength, elasticity and flexibility to the tissue. These cells also secrete modified polysaccharides, which accumulate between cells and fibres and act as a matrix.

11. What does the question mark represent in the following figure?

a) Mast cell
b) Fibroblast
c) Collagen fibres
d) Macrophage
Answer: b
Clarification: The question mark in the given diagram represents a fibroblast which are cells that produce and secrete fibres. The diagram represents areolar tissue.

12. What is the name of the tissue given in the following figure?

a) Areolar tissue
b) Adipose tissue
c) Bone
d) Cartilage
Answer: b
Clarification: The given diagram represents an adipose tissue. It is located beneath the skin. The cells of this tissue are specialised to store fats. It also acts as an insulator by preventing the loss of heat from the body.

13. Areolar tissue is present beneath the skin.
a) True
b) False
Answer: a
Clarification: Areolar tissue is present beneath the skin. It serves as a support framework for epithelium. It contains fibroblasts, macrophages and mast cells. It is a type of loose connective tissue.

14. What type of tissue does the following diagram represent?

a) Dense regular
b) Dense irregular
c) Loose connective
d) Adipose tissue
Answer: a
Clarification: The given figure represents dense regular connective tissue. In this type of tissue, the collagen fibres are present in rows between many parallel bundles of fibres. Tendons and ligaments are examples of this tissue.

15. What type of tissue does the given figure represent?

a) Dense regular
b) Areolar tissue
c) Dense irregular
d) Adipose
Answer: c
Clarification: The given figure represents dense irregular connective tissue. It has fibroblasts and many fibres that are oriented differently. This tissue is present beneath the skin.

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250+ TOP MCQs on Cell Basics and Answers

Biology Multiple Choice Questions on “Cell Basics”.

1. Cells are the structural unit of life and all the organisms are made of cells.
a) True
b) False
Answer: a
Clarification: Cells are the structural unit of life and all the organisms are made of cells. The size and shapes of the cells vary with organisms and their functions but on a whole most of them have identical components.

2. Which among the following is incorrect about the major discoveries in the history of cell?
a) Robert brown made the most major contribution to the history of cell by discovering nucleus
b) Cell theory was developed by Schleiden and Schwann
c) Virchow introduced the concept that genetic material is present inside the nucleus
d) Robert Hooke discovered cell in 1665
Answer: c
Clarification: Robert Hooke discovered cell in 1665. Robert brown made the most major contribution to the history of cell by discovering nucleus. Cell theory was developed by Schleiden and Schwann. Virchow stated that the new cells arise from the pre-existing cells.

3. Which among the following is incorrect about types of cells?
a) In a prokaryotic cell membrane-bound organelles are absent
b) Monera is an example of prokaryotic cell
c) Eukaryotic cells contain membrane-bound organelles
d) Prokaryotic cells contain either RNA or DNA
Answer: d
Clarification: In a prokaryotic cell membrane-bound organelles are absent. Monera is an example of prokaryotic cell. Eukaryotic cells contain membrane-bound organelles. Prokaryotic cells contain both RNA and DNA.

4. Which among the following is incorrect about different types of cells?
a) Size and shape of the cells vary with the functions they perform
b) In unicellular organism a single cell constitutes the entire organism
c) The components in all eukaryotic cells are more/less the same
d) Centrioles are present in plant cells but absent in animal cells
Answer: d
Clarification: Size and shape of the cells vary with the functions they perform. In unicellular organism a single cell constitutes the entire organism. The components in all eukaryotic cells are more/less the same. Centrioles are present in animal cells but absent in plant cells.

5. Active transport requires energy to transport particles from lower concentration to higher concentration.
a) True
b) False
Answer: a
Clarification: Active transport requires energy to transport particles from lower concentration to higher concentration. In passive transport, cell doesn’t expend any energy to transport particles across cells.

6. Energy for the transport of particles through active mode is derived from _______
a) ATP
b) ADP
c) Glucose
d) Lactic acids
Answer: a
Clarification: Energy for the transport of particles through active mode is derived from ATP. In active mode of transportation, the transport of particle takes place against the concentration gradient. Therefore, active transport requires energy to transport particles.

7. Which among the following statements is incorrect about plasma membrane?
a) Plasma membrane is a selectively permeable membrane and allows only those particles that protect the cell
b) Movement of air and water takes place through diffusion and osmosis respectively
c) Osmosis and diffusion are examples of active transport
d) Active transport takes place through use of energy
Answer: c
Clarification: Plasma membrane is a selectively permeable membrane and allows only those particles that protect the cell. Movement of air and water takes place through diffusion and osmosis respectively. Osmosis and diffusion are examples of passive transport. Active transport takes place through use of energy.

8. Which among the following is incorrect about the structure of plasma membrane?
a) Plasma membrane is made of lipids and proteins
b) Lipids with hydrophobic and hydrophilic end are called amphipathic lipids
c) The plasma membrane is a lipid bilayer membrane
d) The proteins that are present on the surface of the plasma membrane are called integral proteins
Answer: d
Clarification: Plasma membrane is made of lipids and proteins. Lipids with hydrophobic and hydrophilic end are called amphipathic lipids. The plasma membrane is a lipid bilayer membrane. The proteins that are present on the surface of the plasma membrane are called integral proteins.

9. Which among the following is incorrect about fluid mosaic model?
a) Plasma membrane was coined by Singer and Nicholson to be a fluid mosaic model
b) According to this model, the proteins are dispersed randomly on the surface and the interior of the plasma membrane
c) The word fluid in this model refers to the fluid flexible nature of the plasma membrane
d) The model fails to explain the cell growth and cell division
Answer: d
Clarification: Plasma membrane was coined by Singer and Nicholson to be a fluid mosaic model. According to this model, the proteins are dispersed randomly on the surface and the interior of the plasma membrane. The word fluid in this model refers to the fluid flexible nature of the plasma membrane. The model explains the cell growth and cell division.

10. Which among the following is incorrect about the layers of the cell wall?
a) The cell wall is made of three main layers, namely, primary cell wall, secondary cell wall and middle lamella
b) Cell wall of a young plant is made of primary cell which composes a loose network of cellulose microfibrils
c) Secondary cell wall forms as the cell matures and composes cellulose and lignin
d) Middle lamella separates cells and is composed of sodium acetate
Answer: d
Clarification: The cell wall is made of three main layers, namely, primary cell wall, secondary cell wall and middle lamella. Cell wall of a young plant is made of primary cell which composes a loose network of cellulose microfibrils. Secondary cell wall forms as the cell matures and composes cellulose and lignin. Middle lamella separates cells and is composed of calcium pectate.

11. Which among the following is incorrect about cell wall?
a) Cell wall provides mechanical supports and avoids rupture of cell in a hypotonic solution
b) Plasmodesmata are protein granules in the cell wall that provides mechanical support
c) Cell wall prevents the cell from invasion and injury
d) Cell wall is entirely permeable and rigid
Answer: b
Clarification: Cell wall provides mechanical supports and avoids rupture of cell in a hypotonic solution. Plasmodesmata are tiny hole like structures that connects the cell walls of adjacent cells and facilitates communication between the cells. Cell wall is entirely permeable and rigid.