This includes questions from Class 11 Biology chapters.
Q 1: Assertion (A): Taxon and taxonomic category are the same things.
Reason (R): Aves is a taxon that includes the category “birds.”
Reason (R): Aves is a taxon that includes the category “birds.”
(1) Both A and R are true and R is the correct explanation of A
(2) Both A and R are true but R is NOT the correct explanation of A
(3) A is true but R is false
(4) Both A and R are false
✅ (4) Both A and R are false
▶️ Both taxon and category refer to hierarchical classifications, but they are not identical.
▶️ A taxonomic category represents a rank or level within the hierarchical classification system. E.g., phylum, class, order, family, genus, species.
▶️ A taxon represents a group of organisms that is assigned to a specific category. E.g., the taxon for birds is Aves, and the category is class.
Q 2: Assertion (A): Archaebacteria live in harshest habitats.
Reason (R): They have a different cell wall structure for their survival in extreme conditions.
Reason (R): They have a different cell wall structure for their survival in extreme conditions.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
▶️ Archaebacteria live in harshest habitats such as extreme salty areas (halophiles), hot springs (thermoacidophiles) and marshy areas (methanogens).
▶️ Archaebacteria have a different cell wall structure for their survival in extreme conditions.
▶️ Methanogens are present in the guts of ruminant animals (cows, buffaloes etc). They produce methane (biogas) from the dung of these animals.
Q 3: Assertion (A): Mosses have important role in plant succession on bare rocks or soil.
Reason (R): Since mosses form dense mats on the soil, they can prevent soil erosion.
Reason (R): Since mosses form dense mats on the soil, they can prevent soil erosion.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (1) Both A and R are true but R is NOT the correct explanation of A
Mosses are ecologically important because of their role in plant succession on bare rocks/soil. Mosses along with lichens decompose rocks making the substrate suitable for the growth of higher plants.
Q 4: Assertion (A): Birds and mammals are cold-blooded (poikilothermous) animals.
Reason (R): They maintain a relatively constant body temperature regardless of external conditions.
Reason (R): They maintain a relatively constant body temperature regardless of external conditions.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (3) A is false but R is true
▶️ Birds and mammals are warm-blooded (homoiothermous) animals. i.e., they can maintain a constant body temperature.
▶️ Poikilotherms (cold-blooded): Animals that lack the capacity to regulate their body temperature. E.g., Pisces, Amphibians, Reptiles.
Q 5: Assertion (A): Cyclostomes sucks food instead of chewing.
Reason (R): They have circular mouth without jaws.
Reason (R): They have circular mouth without jaws.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
▶️ Cyclostomes are ectoparasites on some fishes.
▶️ Elongated body without scales and paired fins.
▶️ 6-15 pairs of gill slits for respiration.
▶️ Sucking and circular mouth without jaws.
▶️ Cartilaginous cranium and vertebral column.
▶️ Circulation is closed type.
▶️ E.g. Petromyzon (Lamprey) and Myxine (Hagfish).
Q 6: Assertion (A): Flowers of plants such as mustard, datura and chilli are Zygomorphic in symmetry.
Reason (R): In Zygomorphic symmetry, a flower can be divided into two similar halves only in a particular vertical plane.
Reason (R): In Zygomorphic symmetry, a flower can be divided into two similar halves only in a particular vertical plane.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (3) A is false but R is true
Based on symmetry, flowers are 3 types:
▶️ 1. Actinomorphic (radial symmetry): Here, a flower can be divided into 2 equal radial halves in any radial plane passing through the centre. E.g. mustard, datura, chilli.
▶️ 2. Zygomorphic (bilateral symmetry): Here, a flower can be divided into two similar halves only in a particular vertical plane. E.g. pea, gulmohur, bean, Cassia.
▶️ 3. Asymmetric (irregular): Here, a flower cannot be divided into two similar halves by any vertical plane passing through the centre. E.g. canna.
Q 7: Assertion (A): In grasses, some specialised cells called bulliform cells regulate water loss.
Reason (R): When Bulliform cells absorb water, the leaf surface is exposed; when flaccid due to water stress, leaves curl inwards.
Reason (R): When Bulliform cells absorb water, the leaf surface is exposed; when flaccid due to water stress, leaves curl inwards.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
▶️ In grasses, certain adaxial epidermal cells along the veins modify into large, empty, colourless cells called bulliform cells.
▶️ When they absorb water and are turgid, the leaf surface is exposed. When they are flaccid due to water stress, leaves curl inwards to minimise water loss.
Q 8: Assertion (A): Frogs exhibit sexual dimorphism.
Reason (R): Female frogs have sound producing vocal sac and a copulatory (nuptial) pad on the first digit of fore limbs.
Reason (R): Female frogs have sound producing vocal sac and a copulatory (nuptial) pad on the first digit of fore limbs.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (2) A is true but R is false
Male frogs have sound producing vocal sac and a copulatory (nuptial) pad on the first digit of fore limbs. These are absent in female frogs.
Q 9: Assertion (A): Mitochondria are known as ‘power houses’ of the cell.
Reason (R): The mitochondria can divide by fission.
Reason (R): The mitochondria can divide by fission.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (1) Both A and R are true but R is NOT the correct explanation of A
Mitochondria are the sites of aerobic respiration. They produce energy in the form of ATP. So they are called ‘power houses’ of the cell.
Q 10: Assertion (A): Lipids are not strictly macromolecules.
Reason (R): Molecular weights of lipids do not exceed 800 Dalton.
Reason (R): Molecular weights of lipids do not exceed 800 Dalton.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
Lipids are not strictly macromolecules as their molecular weights do not exceed 800 Da. But they come under acid insoluble fraction because many lipids are arranged into structures like cell membranes. When a tissue is grinded, cell membranes are broken and form water insoluble vesicles. They cannot be filtered along acid soluble fraction.
Q 11: Assertion (A): Liquid endosperm in coconut is multinucleate.
Reason (R): In this, cytokinesis occurs but no karyokinesis.
Reason (R): In this, cytokinesis occurs but no karyokinesis.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (2) A is true but R is false
▶️ In some organisms, karyokinesis is not followed by cytokinesis. As a result, multinucleate condition (syncytium) arises.
▶️ E.g. Liquid endosperm in coconut. It results from free nuclear divisions (karyokinesis) without subsequent cytokinesis, leading to the absence of cell walls between the cells in the endosperm.
Q 12: Assertion (A): Photorespiration is a wasteful process.
Reason (R): In Photorespiration, there is no synthesis of sugars, ATP and NADPH.
Reason (R): In Photorespiration, there is no synthesis of sugars, ATP and NADPH.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
▶️ In C3 plants, some O2 bind to RuBisCO. Hence CO2 fixation is decreased. Here RuBP binds with O2 to form one molecule of phosphoglycerate and phosphoglycolate. This pathway is called photorespiration.
▶️ In this, there is no synthesis of sugars, ATP and NADPH. Hence photorespiration is a wasteful process. Rather it causes the release of CO2 by using ATP.
Q 13: Assertion (A): R.Q of fats are generally less than 1.
Reason (R): Fats require only less oxygen for their complete oxidation compared to carbohydrates.
Reason (R): Fats require only less oxygen for their complete oxidation compared to carbohydrates.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (2) A is true but R is false
▶️ Respiratory quotient (RQ) is the ratio of the volume of CO2 evolved to the volume of O2 consumed in respiration.
▶️ RQ for carbohydrates= 1
▶️ RQ for fats = less than 1
▶️ RQ for proteins = 0.9
▶️ Fats and proteins require more oxygen for their complete oxidation compared to carbohydrates.
Q 14: Assertion (A): Differentiation in plants is open.
Reason (R): Cells/tissues arising out of the same meristem have different structures at maturity.
Reason (R): Cells/tissues arising out of the same meristem have different structures at maturity.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
▶️ Differentiation is the process in which the cells in meristems (root apical & shoot-apical) and cambium differentiate and mature to perform specific functions.
▶️ Under certain conditions, living differentiated cells regain the capacity of division. It is called dedifferentiation.
▶️ The dedifferentiated cells can divide and produce cells that again lose the capacity to divide but mature to perform specific functions. It is called redifferentiation.
Q 15: Assertion (A): In tissues, oxyhaemoglobin dissociates to release O2.
Reason (R): In tissues, low pO2, high pCO2, high H+ ions and high temperature exist.
Reason (R): In tissues, low pO2, high pCO2, high H+ ions and high temperature exist.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
▶️ In the alveoli, high pO2, low pCO2, lesser H+ ion concentration and lower temperature exist. These factors are favourable for the formation of oxyhaemoglobin.
▶️ In tissues, low pO2, high pCO2, high H+ ions and high temperature exist. So oxyhaemoglobin dissociates to release O2.
Q 16: Assertion (A): During Joint diastole, blood from pulmonary vein & vena cava flows into left & right ventricles respectively through left and right atria.
Reason (R): Semilunar valves are closed at this stage.
Reason (R): Semilunar valves are closed at this stage.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (1) Both A and R are true but R is NOT the correct explanation of A
▶️ Joint diastole is the relaxed state of all chambers of heart.
▶️ During this, tricuspid & bicuspid valves are open. So blood from pulmonary vein & vena cava flows into left & right ventricles respectively through left and right atria.
▶️ Semilunar valves are closed at this stage.
Q 17: Assertion (A): In adult human, normal volume of urine released is limited to 1.5 litres.
Reason (R): About 99% of glomerular filtrate is reabsorbed by the renal tubules.
Reason (R): About 99% of glomerular filtrate is reabsorbed by the renal tubules.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
▶️ The amount of glomerular filtrate formed per minute is called Glomerular filtration rate (GFR).
▶️ Normal GFR = 125 ml/minute, i.e., 180 litres/day.
▶️ But about 99% of this is reabsorbed by the renal tubules. So normal volume of urine released is 1.5 litres.
Q 18: Assertion (A): When muscle fibres contract, H-zone will be disappeared.
Reason (R): During muscle contraction, Ca2+ ions are released from sarcoplasmic cisternae into sarcoplasm.
Reason (R): During muscle contraction, Ca2+ ions are released from sarcoplasmic cisternae into sarcoplasm.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (1) Both A and R are true but R is NOT the correct explanation of A
▶️ An action potential in the sarcolemma of the muscle fibre causes the release of Ca2+ ions from sarcoplasmic cisternae into sarcoplasm.
▶️ Ca binds with a subunit of troponin on actin filaments and unmask the active sites for myosin.
▶️ Using energy from ATP hydrolysis, myosin head binds to active sites on the actin to form cross bridge. This pulls actin filaments on both sides towards the centre of A-band. Actin filaments partially overlap so that H-zone disappears.
Q 19: Assertion (A): Impulse transmission in chemical synapse is faster than that in electrical synapse.
Reason (R): Chemical synapses have synaptic vesicles filled with neurotransmitters.
Reason (R): Chemical synapses have synaptic vesicles filled with neurotransmitters.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (3) A is false but R is true
Synapse is a functional junction between two neurons. It is 2 types:
▶️ 1. Electrical synapses: In this, the membranes of pre- and post-synaptic neurons are in close proximity. So impulse transmission is similar to the transmission along an axon. Impulse transmission is faster than in chemical synapse.
▶️ 2. Chemical synapses: In this, there is a fluid filled space (synaptic cleft) between the presynaptic neuron & postsynaptic neuron. The presynaptic regions have swellings called Synaptic knob (buttons). They contain synaptic vesicles filled with neurotransmitters (acetylcholine or adrenaline).
Q 20: Assertion (A): Adrenaline and Noradrenaline are called hormones of Fight or Flight.
Reason (R): They are rapidly secreted to prepare the body for immediate physical action in response to stress or danger.
Reason (R): They are rapidly secreted to prepare the body for immediate physical action in response to stress or danger.
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
▶️ Adrenal medulla produces catecholamine hormones such as Adrenaline (epinephrine) & Noradrenaline (norepinephrine).
▶️ They are rapidly secreted in response to stress emergency situations so called emergency hormones (hormones of Fight or Flight).
▶️ These increase alertness, pupillary dilation, piloerection (rising of hairs), sweating, heartbeat, heart contraction and respiratory rate. Stimulate glycogenolysis to increase glucose in blood. Also stimulate lipolysis and proteolysis.