CBSE Class 11 Biology Important questions Part 2

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CBSE Class 11 Biology Important questions Part 2

Section A

1. In botanical terminology, the word “phyllotaxy” specifically refers to which of the following plant features?

1. The structure and position of the ovary within a flower
2. The pattern in which leaves are arranged on a stem or branch
3. The morphological classification of a plant’s root system
4. The organization of sepals and petals in a floral whorl

Answer: (b) The pattern in which leaves are arranged on a stem or branch

2. Closed vascular bundles lack

1. pith
2. xylem
3. cambium
4. xylem vessels

Answer: (c) cambium

3. Tendons connect the following:

1. bone to bone
2. muscle to muscle
3. cartilage to muscle
4. bone to muscle

Answer: (d) bone to muscle

4. Identify the chemical composition of the middle lamella.

1. calcium sulphide
2. calcium pectate
3. calcium carbonate
4. calcium chloride

Answer: (b) calcium pectate

5. Regarding enzymes, identify the correct statement from the options provided.

1. Apoenzyme = Holoenzyme + Coenzyme
2. Holoenzyme = Apoenzyme + Coenzyme
3. Coenzyme = Apoenzyme + Holoenzyme
4. Holoenzyme = Coenzyme – Apoenzyme

Ansewr: (b) Holoenzyme = Apoenzyme + Coenzyme

6. Choose the correct sequence. A. Pachytene B. Zygotene C. Leptotene D. Diakinesis E. Diplotene

1. C, B, A, D, E
2. C, A, B, E, D
3. C, B, A, E, D
4. D, B, C, E, A

Answer: c) C,B,A,E,D

7. Mobilization of stored food in germinating seeds is triggered by

1. auxins
2. cytokinins
3. gibberellins
4. ethylene

Answer: (c) gibberellins

CBSE Class 11 Biology Important questions Part 2

8. The edible part in mango is 

1. tegmen
2. Epicarp
3. Mesocarp
4. endocarp

Answer: (c) Mesocarp

9. The type of cells, which line the inner surface of fallopian tubes and bronchioles is

1. Stratified squamous epithelial cells
2. Simple squamous epithelial cells
3. Simple cuboidal epithelial cells
4. Ciliated epithelial cells

Answer: b) Ciliated epithelial cells

10. Match the following:

i	Cisternae	a	Infoldings in mitochondria
ii	Thylakoids	b	Flat membranous sacs in stroma
iii	Cristae	c	Disc shaped sacs in Golgi apparatus

Answer: i- c, ii- a, iii-b

11. State the ATP and NADPH₂ requirements for fixing one CO₂ molecule in the Calvin cycle.

1. 1 ATP, 2 NADPH2
2. 2 ATP, 3 NADPH2
3. 3 ATP, 2 NADPH2
4. 2 ATP, 2 NADPH2  

Answer: c) 3 ATP, 2 NADPH2

12. Mark the odd one in the following

1. Oxaloacetic acid
2. citric acid
3. succinic acid
4. pyruvic acid

Answer: d) pyruvic acid

CBSE Class 11 Biology Important questions Part 2

13. To increase sugar production in sugarcanes, they are sprayed with

1. ethylene
2. IAA
3. Gibberellin
4. cytokinin        

Answer: c) Gibberellin             

14. What will be the PO₂ and pCO₂ in the atmospheric air compared to those in the alveolar air?

1. PO₂ lesser PCO₂ higher
2. PO₂ higher PCO₂ lesser
3. PO₂ higher PCO₂ higher
4. PO₂ lesser PCO₂ lesser  

Answer: b) P O2  higher  P CO2 lesser

15. Angiotensinogen is a protein produced and secreted by

1. Juxtaglomerular (JG) cells
2. Macula dense cells
3. Endothelium of blood vessels
4. Liver cells

Answer: d) Liver cells

16. Deficiency of parathormone produces muscle cramps (tetany) due to 

1. Enhanced levels of Na⁺ in  blood
2. Lowered levels of blood glucose
3. Enhanced levels of blood Ca²⁺
4. Lowered levels of blood Ca²⁺

Answer: d) Lowered levels of blood Ca²⁺

17. The morphological nature of the edible part of a coconut is

1. Cotyledon
2. Perisperm
3. Pericarp
4. Endosperm

Answer: d). endosperm

18. Antibodies are chemically_ _ _ _ _ _ _ _ _.

1. fats
2. Foreign
3. pathogensActin
4. Protein

Answer: d). protein

CBSE Class 11 Biology Important questions Part 2

19. Which of the following are not membrane-bound ORGANELL?

1. Ribosomes
2. Mesosomes
3. Vacuoles
4. Lysosomes

Answer: a). Ribosomes

20. The longest stage in the cell cycle is

Interphase

Anaphase

Metaphase

None of the above

Answer: a). Interphase

21. Malacophily means

1. pollination by wind
2. pollination by water
3. pollination by snails
4. pollination by animals

Answer: c). pollination by snails

22. Typical plant growth shows

1. J-shaped curve
2. S-shaped curve
3. I-shaped curve
4. Parabolic curve

Answer: b). S- shaped curve

23. In brain, respiratory control centre lies in

1. pons
2. medulla oblongata
3. hypothalamus
4. cerebrum        

Answer: b). Medulla oblongata

24. Kidneys are located in

1. thoracic cavity
2. abdominal cavity
3. body cavity
4. pelvic cavity

Answer: b). abdominal cavity

25. Match the columns.

A	Hinge Joint	1	Carpals
b	Saddle Joint	2	Knee
c	Pivot Joint	3	Thumb
d	Gliding Joint	4	Vertebra

CBSE Class 11 Biology Important questions Part 2

1. A-4, B-3, C-1, D-2
2. A-3, B-1, C-2, D-4
3. A-2, B-3, C-4, D-1
4. A-3, B-1, C-4, D-2

Answer: C). A-2, B-3, C-4, D-1

26. Which is an emergency hormone?

1. Norepinephrine
2. Androgen
3. Cortisol
4. FSH

Answer: a). Norepinephrine

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CBSE Class 11 Biology Important questions Part 2

Section B

1. Name the stages of cell division at which these events occur-

1. Disappearance of nuclear membrane
2. Crossing over between non-sister chromatids
3. Terminalisation of Chiasmata
4. Homologous chromosomes separate and move to opposite poles of the spindle.

Answer:

a. Prophase

b. Pachytene of Prophase I

c. Diakinesis of Prophase I

d. Anaphase I

2. Select the appropriate plant growth regulator for the given situation.

1. Induce rooting in a twig
2. Quickly ripen a fruit
3. Increase yield of sugarcane
4. Bolt a rosette plant

Answer:

1. Auxin
2. Ethylene
3. Gibberellin
4. Gibberellin

CBSE Class 11 Biology Important questions Part 2

1. What is meant by reabsorption in urine formation?
2. Identify the two types of reabsorption.

Answer:

1. Glomerular filtrate contains substances the body needs like essential ions, glucose, amino acids, and smaller proteins in addition to wastes. This needed substances and some waters are reabsorbed into adjacet blood capillaries.
2. Active reabsorption of Glucose, amino acids, Na⁺ etc.
   • Passive water reabsorption.

4. A cyclic process is occurring in C₃ plant, which is light dependent and needs O₂. This process consumes energy instead of generating it.

(a) Name the process.

(b) List the final products of the process.

Answer:

(a) Photorespiration

(b) Products – Carbon dioxide, 3 Phosphoglycerate and Phosphoglycerate

5. ATPase enzyme consists of two parts. What are those parts? How are they arranged in the thylakoid membrane and in which part of the enzyme conformational change occur?

Answer: ATPase enzyme consists of two components: F₀ and F₁.

F0 is embedded in the thylakoid membrane where it forms a transmembrane channel that facilitates diffusion of protons across the membrane. F₁ is located on the outer surface of the thylakoid membrane.

The conformational changes take place in the F1 segment of the ATPase enzyme.

CBSE Class 11 Biology Important questions Part 2

6. State universal rules of nomenclature.

Answer:

1. Written in italics
2. First word is genus and the second is species epithet.
3. When handwritten should be underlined separately
4. Generic name starts with a capital letter and specific name with a small letter.

7. Classify the chromosomes based on the positions of centromeres.

Answer: Telocentric, Acrocentric, Submetacentric, Metacentric

8. What is meant by tertiary structure of proteins?

Answer: Three-dimensional compact structure

Hydrophobic side chains held interior and hydrophilic groups held outside.

9. How is arithmetic growth different from geometric growth?

Answer: In arithmetic growth following mitotic cell division, only one daughter cell continues to divide while the other differentiates and matures

In geometric growth, a sigmoid curve is obtained depicting lag, log and stationary phases.

CBSE Class 11 Biology Important questions Part 2

10. How do you distinguish between a skeletal muscle and a cardiac muscle?

Answer:

Skeletal muscle	Cardiac muscle
Voluntary Unbranched  Multinucleated Intercalated discs absent	Involuntary Branched One or two nuclei Intercalated discs present

11. Diffusion of gases occurs in the alveolar region only and not in other parts of the respiratory system. Why?

Answer:

1. The differences in partial pressure across the respiratory membrane are substantial
2. The distances involved in gas exchange are small
3. The gases are lipid soluble
4. The total surface area is large
5. Blood flow and air flow are coordinated

12. Name the aggregation formed by slime moulds during favourable conditions. What happens to it during the following unfavourable conditions.

Answer: aggregation formed by slime moulds during favourable conditions is called Plasmodium. Unfavorable conditions form fruiting bodies that bears spores at their tips.

a) Name the kind of tissue found at the shoot tip

b) Name the only living cells/ components of xylem

Answer: (a) Meristematic tissue (b) Xylem parenchyma

14. Identify A and B and write one point of difference between them.

Answer:

A-Skeletal muscle

B- Smooth muscle

Feature	Skeletal Muscle (A)	Smooth Muscle (B)
Shape	Long, cylindrical fibres	Spindle-shaped (tapered ends)
Striations	Present	Absent
Control	Voluntary	Involuntary

CBSE Class 11 Biology Important questions Part 2

15. Mention the two steps in glycolysis, where ATP is consumed.

Answer:

(i) Conversion of glucose into pyruvic acid

(ii) Conversion of fructose 6 phosphate into fructose 1,6- biphosphate

16. Describe the incomplete double circulation with an example.

Answer: Atria of the heart receives oxygenated and deoxygenated blood separately but the two get mixed up in ventricle which pumps out mixed blood. Eg. Amphibians.

17. Define the terms phycobiont and mycobiont.

Answer: The algal component of the lichens is known as phycobiont, while the fungal component is known as mycobiont.

Both the algae and the fungi live in symbiotic association with each other. The algae prepare food for the fungi and the fungi, in turn, provides shelter and absorbs nutrients from the soil.

18.  Why are phloem and xylem, complex tissues?

Answer: Xylem and phloem are made up of more than one type of cells. 

Xylem serves to transport water and minerals and contributes to plant support. It is made up of tracheid’s, xylem parenchyma, and xylem fibers.

Phloem conducts food materials to various parts of the plant. It comprises of sieve tubes, phloem parenchyma, companion cells, and phloem fibers.

19. Mention the cellular components of blood.

Answer: Blood contains the following components:

•     Plasma

•     Red Blood Cells

•     White Blood Cells

•     Platelets

20. On what factor the respiratory quotient depends?

Answer: Respiratory quotient is the ratio of the volume of carbon dioxide evolved to that of oxygen consumed by an organism, tissue, or cell in a given time. The respiratory quotient is determined by oxygen consumed and carbon dioxide produced.

21. Write about three valves in the heart.

Answer:

The right atrium and ventricle are separated by the tricuspid valve.

Between the right ventricle and the pulmonary artery lies the pulmonary semilunar valve.

The left atrium and ventricle are connected by the mitral valve.

Situated between the left ventricle and the aorta is the aortic semilunar valve.

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Section c

1. Why is sinoatrial node known as pacemaker of the heart?
2. Veins have valves in them where as arteries do not? Why?
3. Blood clotting depends on which vitamin and mineral ion?

Answer:

1. SA node in heart is responsible for initiating and maintaining rhythmic activity of heart.
2. Veins have valves in them because blood flow in them with low pressure so to prevent the back flow of blood they have valves in them arteries do not have valves because blood flows in it at high pressure so no chance of back flow.
3. Vitamin-K and Ca²⁺ ion.

2. During a street fight between two individuals, mention the effects on the following organs by the ANS in the table given below. A sample is provided for reference.

Organ	Sympathetic Nerves	Parasympathetic nerves
Eg: Lungs	Dilates bronchi and bronchioles	Constricts bronchi and bronchioles
1. Heart	A	B
2. Pupil of eye	C	D
3. Salivary gland	E	F

Answer:

A – Accelerates heartbeat

B – Retards heartbeat

C – Dilates pupil

D – Constrict pupil

E – Inhibits the secretion of saliva causing the drying of the mouth

F – Stimulates the release of saliva

3. Draw the structure of a Sarcomere of muscle fibers showing the muscle during relaxation and labelled Z line, M line, H zone, A band and I band.

Answer:

Answer:

1. A – G1 or Gap 1 phase

        B – S or Synthetic phase

        C – G2 or Gap 2 phase

        D – M or Mitosis phase

2. G0 or quiescent phase is the stage where the cells remain metabolically active but do not replicate unless called to do so.

5. The diagram below represents the changes in the number of chromosomes during several processes that occur in an animal.

Answer:

(a) X – Mitosis; Y – Meiosis

(b) During mitosis the number of chromosomes in daughter cells are same as that of mother cell whereas in meiosis the number of chromosomes in daughter cell is reduced to halved as that of mother cell. Pairing and separation of homologous chromosomes do not occur in mitosis where as pairing and separation of homologous chromosomes occur in meiosis.

6. Mention the name and source of the hormone which regulates the following:

1. Basal metabolic rate in the body
2. Maturation of Graafian follicle
3. Milk secretion in human female
4. Prepares the body for facing emergency situation
5. Raise the level of calcium ion in blood
6. Increase blood glucose level

Answer:

1. Thyroxin secreted by thyroid gland
2. Follicle Stimulating Hormone (FSH) secreted by the anterior pituitary gland.
3. Prolactin is a hormone secreted by the pituitary gland
4. Adrenaline hormone secreted by adrenal gland
5. Parathyroid hormone (PTH) secreted by the parathyroid glands
6. Glucagon secreted by pancreas

7. What happens to the Pyruvate when it enters into mitochondrial matrix during aerobic respiration? Explain.

Answer: Oxidative decarboxylation.  Pyruvic acid with coenzyme A and  NAD+ forms acetyl CoA, CO2, NADH + H+ in the presence of Pyruvate dehydrogenase and Mg2+. During this process two molecules of NADH are produced from the metabolism of two molecules of Pyruvic acid /explanation in Equation can be considered.

1. What are heterocysts?
2. What is a viroid?
3. What are aplanospores?

Answer:

i)  Heterocysts are specialized cells in certain cyanobacteria that fix nitrogen.

ii) Viroids are agents of infectious disease in plants. They lack a capsid. 

iii)  Aplanospores lack motility.

9. In which plant will you look for Mycorrhiza and coralloid roots? Additionally, define these terms.

Answer: Mycorrhiza is an association between fungus and roots of higher plants like Pinus

Coralloid roots: Coral like roots are irregular and branched, They are present in Cycas.

10. Frogs are capable of respiration both on land and in water. Describe the different methods used by them for respiration.

Answer: In water, frogs respire cutaneously through their skin.

On land, buccal cavity, skin and lungs act as respiratory organs, pulmonary respiration.

11. Enumerate the different classes of enzymes.

Answer:

1.         Oxidoreductase

2.         Transferases

3.         Hydrolases

4.         Isomerases

5.         Lyases  

6.         Ligases 

12. Aquatic animals are generally ammonotelic in nature whereas terrestrial forms are not. Comment. 

Answer: Ammonia excretion demands significant water volume.

Terrestrial animals do not get sufficient amount of water, They are either ureotelic or uricotelic

13. What are Plant growth regulators?

Answer: Plant growth regulators also referred to as phytohormones or plant hormones.  They are a group of organic compounds, which functions by controlling and modifying the physiological processes like the growth, development, and movement of plants.

13. List the following steps in a sequential manner for the completion of the respiration process.

1. Gas exchange across the alveolar membrane.
2. Transportation of gases by blood
3. Cells use oxygen for catabolism, producing CO₂ as a byproduct.
4. Pulmonary ventilation involves inhaling atmospheric air and exhaling CO₂-rich alveolar air.
5. Diffusion of oxygen and carbon dioxide between tissues and blood

Answer:

d) Pulmonary ventilation involves inhaling atmospheric air and exhaling CO₂-rich alveolar air.

a) Gas exchange across the alveolar membrane.

b)   Transportation of gases by blood

e) Diffusion of oxygen and CO2 between tissues and blood

c) Cells use oxygen for catabolism, producing CO₂ as a byproduct.

14. How could it affect a person’s CNS if he is attacked by a blow on the back of the neck?

Answer: It would lead to an impairment of cognitive abilities or dysfunctionalities physically. (This may also disrupt emotional or behavioral functioning. Cervical damages can lead to tetraplegia.

(i) Name the causative agent of ‘bakane’disease in rice seedlings.

(ii) Name the stress hormone sound in plants.

(iii) Name the PGR that increase yield of sugarcane.

Answer:

(i) Gibberella fujikuroi

(ii) Abscisic acid

(iii) Gibberellins

(i) List two factors which affect the rate of diffusion of  gas in lungs.

(ii) What is the term given to the maximum volume of air, a person can breathe in after a forceful expiration

(iii)What is one of the major causes of emphysema?

Answer:

   (i) There are several factors that affect the rate of diffusion in the lungs:–

• The thickness of the membrane: The rate of diffusion is faster as the membrane gets thinner.
• The surface area of membrane: The rate of diffusion is faster when the surface area is larger.
• Diffusion coefficient of the gas: This determines the expanse over which the gas can diffuse.
• The pressure difference across the membrane: This determines the speed and rate at which the gas diffuses.

(ii) Vital Capacity

(iii) Cigarette smoking

(i) Why is the cerebral cortex referred to as grey matter too?

(ii) Mention any two functions of the association areas of cerebral cortex.

(iii)Why does cerebellum have a very convoluted surface?

Answer:

(i) Contains cell bodies of the neurons, which give a greyish appearance 

(ii)Intersensory association, memory , communication.

(iii)To provide accommodation for a large number of neurons.

18. What do you mean by phyllotaxy?

Answer: The arrangement of leaves on the stem of branch is termed phyllotaxy. There are generally three categories:

(a)  Alternate: A single leaf arises at each node in an alternate manner, as in a china rose.

(b) Opposite phyllotaxy: two leaves per node, positioned opposite each other (e.g., Calotropis, guava).

(c) Whorled phyllotaxy features three or more leaves at a node (e.g., Alstonia).

19. What is the significance of meiosis.

Answer:   (a)        Alternate phyllotaxy has one leaf per node (e.g., china rose).

(b)       In opposite arrangement, each node bears two leaves facing each other (e.g., Calotropis, guava).

(c)        Whorled phyllotaxy: multiple leaves per node arranged in a circle (e.g., Alstonia).

20. (a)Name the stage of cell cycle at which each of the following events occur:
    • Chromosomes are moved to spindle equator
    • Centromere splits and chromatids separate 

(b) What are chiasmata? What is their significance.

Answer:  (a)(i) Metaphase.

(ii) Anaphase of mitosis and anaphase II of meiosis.

(b) X shaped structures formed at the point of crossing over. They represent the sites of cross overs and hence exchange of genetic material or recombination

21. In which type of fermentation, no CO2 is released? Name the enzyme required for it. Give its complete reaction.

Answer: Lactic acid fermentation

Enzyme – Lactate dehydrogenase

Equation:

22. Fill in the blanks at A, B, C, D, E and F and complete the C4 pathway/Hatch-Slack pathway.

Atmospheric CO2 enters (A)

CO2 is accepted by (B) and forms compound (C)

(C) enters into (D) and splits into CO2 and (E)

CO2 enters Calvin cycle and (E)regenerates (F)

Answer:

A – Mesophyll cell

B – Phosphoenol pyruvate (PEP)

C – Oxaloacetic acid (OAA)

D – Bundle sheath cell

E – C3 acid

F – Phosphoenol pyruvate (PEP)

23. Explain cyclic photophosphorylation along with its pathway.

Answer:

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Section D

1. The conifer forests of the world cover huge areas of land and provide the largest terrestrial carbon sink. Conifers are also valued economically; their softwood is used for the production of timber, they are used to cultivate pine nuts, and the berries of the juniper bush are used to flavour gin. Like other vascular plants, gymnosperms exhibit a sporophyte-dominant life cycle, where the diploid sporophyte forms the main plant body. The gametophyte stage is brief and involves gamete production within reproductive structures.       

1.  A plant classified as dioecious must meet the following condition:

1.  Reproduce asexually
2. Have both male and female organs
3. Have separate male and female individuals
4. Not reproduce

 Answer: (c) Have separate male and female individuals

2. Which division of the gymnosperms is most commonly used to create paper? 

1. Conifers
2. Cycads
3. Gnetophyta
4. Gingkophyta

Answer:  (a) Conifers

3. Describe the function of cones in the gymnosperm life cycle.

1. It is the seed
2. It is the male gametophyte
3. It is the reproductive body
4. It feeds the embryo

Answer: (c) It is the reproductive body

4. Conifers are adapted to tolerate extreme environmental conditions because of-

1. broad hardy leaves.
2. superficial stomata.
3. thick cuticle.
4. presence of vessels.

Answer: (c) thick cuticle

            OR

5. Cycas and Adiantum resemble each other in having:

1. seeds
2. motile sperms
3. cambium
4. vessels

Answer: (b) motile sperms

2. The thyroid gland has two lobes positioned on each side of the trachea. Both the lobes are interconnected with a thin flap of connective tissue called isthmus. Thyroid tissue consists of follicles and surrounding stroma. Each thyroid follicle is formed by a layer of follicular cells surrounding a central lumen. The follicular cells produce two key hormones: thyroxine (T₄) and triiodothyronine (T₃). Adequate iodine is needed for proper thyroid hormone production. Dietary iodine deficiency can lead to hypothyroidism and thyroid gland enlargement, known as goitre. Hypothyroidism during pregnancy causes defective development and maturation of the growing baby leading to stunted growth (cretinism), mental retardation, low intelligence quotient, abnormal skin, deaf-mutism, etc. In adult women, hypothyroidism may cause the menstrual cycle to become irregular. Thyroid cancer or nodule formation can cause excessive hormone production, resulting in hyperthyroidism, which disrupts normal physiological function. Exophthalmic goitre is a form of hyperthyroidism, characterised by enlargement of the thyroid gland, protrusion of the eyeballs, increased basal metabolic rate, and weight loss, also called Graves’ disease. Thyroid hormones regulate basal metabolic rate, aid in red blood cell production, and influence carbohydrate, protein, and fat metabolism. Thyroid hormones also contribute to fluid and electrolyte balance. Additionally, the thyroid produces thyrocalcitonin, a protein hormone that regulates blood calcium levels.

1. _______________ Protein hormone secreted by thyroid gland regulates the blood calcium levels along with PTH.

1. thyromelatonin
2. thyrocalcitonin
3. thyrocalciumtonin
4. thyrocarbotonin

2. cretinism is referred as:

1. Growth retardation caused by iodine deficiency.
2. stunned growth due to deficiency of thyroid hormones
3. Cognitive impairment resulting from iodine deficiency.
4. deaf- mutism due to deficiency of iodine

3. Explain how both lobes of the thyroid gland are interconnected?
4. Give the composition of thyroid follicles and their functions.

Answer:

1. b
2. a
3. Thyroid gland is composed of two lobes. A thin connective tissue band known as the isthmus connects the two lobes.
4. Thyroid follicle is made up of follicular cells.

3. Lipids form a heterogeneous group but all are made up of carbon hydrogen and oxygen. These are insoluble in water and soluble in organic solvents like acetone, ether, alcohol etc. Oxygen atoms are far fewer in number than carbon atoms. They need a large amount of oxygen for their oxidation to release energy. Lipids are classified as simple, compound, or derived. Simple lipids consist of fatty acids esterified with alcohols. Compound lipids are formed when simple lipids combine with another compounds for example glycolipids, phospholipids and lipoproteins. Derived lipids are of various types and important example being steroids.

1.  Lipids mainly consist of

1. Carbon only
2. carbon hydrogen and nitrogen
3. carbon hydrogen and oxygen
4. Hydrogen only

Answer: C) carbon hydrogen and oxygen               

2. Among the given options non-polymeric molecule is

1. Nucleic acids
2. proteins
3. Lipids
4. polysaccharides

Answer: C) Lipids                                   

3.  An example of unsaturated fatty acid is

1. Oleic acid
2. Stearic acid
3. Linoleic acid
4. both a and c

Answer: D) both a and c

4. In lipids, the ratio of carbon atoms to oxygen atoms is relatively.

1. same
2. much less
3. much more
4. none of these.

Answer: C) much more                            

                OR

5. Steroids are an example of

1. Derived lipids
2. Conjugated lipids
3. Simple lipids
4. Lipo protein

Answer: A) derived lipids   

4. Algae are a diverse group of aquatic organisms that have the ability to conduct photosynthesis, they are unicellular or multicellular and undifferentiated organisms that occur in a variety of forms and sizes. Algae belong to a polygenetic group. Algae are classified into three main groups based on their pigments, chemical composition, and stored food reserves. Chlorophyceae, phaeophycean and Rhodophyceae. The members of these classes also differ in cell wall composition, stored food material, body structure , mode of reproduction , etc. 

1. Provide an example of an organism belonging to the class Rhodophyceae.  

1. Spirogyra
2. fucus
3. Polysphonia
4. Chlorella 

Answer: c) Polysphonia

2. Multicellular saline forms are found in 

1. Rhodophyceae
2. Chlorophyceae
3. Phaeophyceae
4. All the above 

Answer: (a) Rhodophyceae 

3. Identify the stored food reserve in the class Phaeophyceae. 

1. mannitol and laminarin
2. floridean starch
3. pyrenoids
4. All of the above 

Answer: (a) mannitol and laminarin

4. Cell wall of Porphyra (red algae) contains 

1. cellulose
2. pectin’s
3. Poly sulphate esters
4. all of these 

Answer: (d) all of these 

5. The detailed structure of the membrane was studied only after the advent of the electron microscope in the 1950s. Meanwhile, chemical studies on the cell membrane, especially in human red blood cells (RBCs), enabled the scientists to deduce the possible structure of the plasma membrane. Research has revealed that the cell membrane consists of lipids, proteins, and carbohydrates.

1. What part of the plasma membrane forms a bilayer structure?

1.  Nucleic acid
2. Lipid
3. Protein
4. Carbohydrate

Answer: b. Lipid

2. The membrane’s lipid layer is primarily made up of __________.

1. Phosphoglycerides
2. Amino acids
3. polysaccharides
4. Glycoproteins

Answer: a. Phosphoglycerides

3. What proportion of the human red blood cell membrane is composed of proteins?

1. 40
2. 70
3. 52
4. 66

Answer: c. 52

4. Membrane proteins are categorized into ________ types based on how easily they can be extracted.

1. Three
2. Two
3. Four
4. Five

Answer: b. Two

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Section E

1. Human blood is classified into ABO and Rh systems based on red blood cell antigens. For a safe transfusion, donor and recipient blood types must be compatible; otherwise, the recipient’s immune system attacks the donor cells, causing clumping that can obstruct circulation.

(a) What complication may arise when an Rh-negative woman and an Rh-positive man have children?

(b) Why O blood group recipients cannot receive other blood types

Answer:

(a) When an Rh-negative mother carries an Rh-positive baby (conceived with an Rh-positive father), Rh incompatibility can occur. During first pregnancies, mixing of blood typically happens only at delivery, prompting the mother to develop Rh antibodies. These antibodies pose no risk to the first child but may attack red blood cells in subsequent Rh-positive pregnancies, leading to a condition called erythroblastosis fetalis.

(b) Type O blood lacks A and B antigens but contains both anti-A and anti-B antibodies. Transfusing any other blood type introduces foreign antigens, triggering the recipient’s antibodies to attack the donor cells, causing agglutination.

2. Summarize the importance of mitosis and meiosis in multicellular life.

Answer:

Significance of mitosis

Growth and repair, reproduction in unicellular organisms.

Significance of meiosis

Maintains same chromosome number, maintains stability of species, variations due crossing over.

3. Create a table to illustrate the various blood groups and compatible donors.

Answer:

Blood group	Antigens	Antibodies	Donor group
A	A	B	A, O
B	B	A	B, O
AB	A,B	Nil	A, B, AB, O
O	Nil	A, B	O

Blood group A: Blood type A carries A antigens and B antibodies, allowing transfusion from A or O donors.

Blood group B: Blood type B has B antigens and A antibodies, so compatible donors are B and O.

Blood group AB: Blood type AB possesses both A and B antigens but lacks A and B antibodies, making it compatible with all blood types—hence known as the universal recipient.

Blood group O: Blood type O has no A or B antigens but contains both antibodies, so it can only receive O blood. However, it can be donated to any blood type, making O the universal donor.

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