This includes questions from Class 11 Biology chapters.
Q 1: Assertion (A): Lichens are very good pollution indicators.
Reason (R): They grow abundantly in polluted areas.
Reason (R): They grow abundantly in polluted areas.
(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) A is false but R is true
✅ (3) A is true but R is false
▶️ Lichens do not grow in polluted areas.
▶️ Lichens are symbiotic associations (mutually useful associations) between algae & fungi.
▶️ The algal component is called phycobiont (autotrophic) and fungal component is mycobiont (heterotrophic).
Q 2: Assertion (A): Chlorella and Spirulina are used as food supplements by space travelers.
Reason (R): They are rich source of carbohydrates.
Reason (R): They are rich source of carbohydrates.
(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) A is false but R is true
✅ (3) A is true but R is false
▶️ Chlorella and Spirulina are rich source of Proteins.
▶️ Benefits of algae:
1. Through photosynthesis, they fix half of the total CO2 on earth and increase the level of dissolved oxygen.
2. Many marine algae (70 species) are used as food. E.g. Porphyra, Laminaria and Sargassum.
3. Agar (from Gelidium & Gracilaria) is used to grow microbes and in ice-creams and jellies.
4. Some marine brown & red algae produce hydrocolloids (water holding substances). E.g. algin (brown algae) and carrageen (red algae).
5. Unicellular algae like Chlorella & Spirulina are used as food supplements by space travelers.
Q 3: Assertion (A): Members of Phaeophyceae vary in colour from olive green to various shades of brown.
Reason (R): Phaeophyceae possess chlorophyll a, c, carotenoids and xanthophylls.
Reason (R): Phaeophyceae possess chlorophyll a, c, carotenoids and xanthophylls.
(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) A is false but R is true
✅ (1) Both A and R are true and R is the correct explanation of A
▶️ Phaeophyceae (brown algae) possesses chlorophyll a, c, carotenoids and xanthophylls.
▶️ They vary in colour from olive green to brown based on the amount of a xanthophyll pigment, fucoxanthin.
Q 4: Assertion (A): Water vascular system is the characteristic feature of Sponges.
Reason (R): Sponges have cellular level of organization.
Reason (R): Sponges have cellular level of organization.
(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) A is false but R is true
✅ (4) A is false but R is true
▶️ Water vascular system is the characteristic feature of Echinodermata.
▶️ In sponges (Porifera), Water canal system is present. Here, water enters through minute pores (ostia) in the body wall into a central cavity (spongocoel), from where it goes out through osculum.
Q 5: Assertion (A): All flatworms have hooks and suckers.
Reason (R): All members of Platyhelminthes are parasites.
Reason (R): All members of Platyhelminthes are parasites.
(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
Hooks and suckers are parasitic adaptations for attachment to their hosts. All flatworms are not parasites (e.g., Planaria ). So they do not have hooks and suckers.
Q 6: Assertion (A): In parietal placentation, ovary is initially one-chambered but it becomes two-chambered.
Reason (R): It can appear to be two-chambered due to the formation of a false septum.
Reason (R): It can appear to be two-chambered due to the formation of a false septum.
(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) A is false but R is true
✅ (1) Both A and R are true and R is the correct explanation of A
Parietal placentation: Here, the ovules develop on the inner wall of the ovary or on peripheral part. Ovary is one-chambered but it becomes two-chambered due to the formation of the false septum. E.g. mustard and Argemone.
Q 7: Assertion (A): In open type vascular bundles, they can form secondary xylem and phloem tissues.
Reason (R): In this, cambium is absent between phloem and xylem.
Reason (R): In this, cambium is absent between phloem and xylem.
(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) A is false but R is true
✅ (3) A is true but R is false
Based on the presence or absence of cambium, vascular bundles are 2 types:
1. Open type: In this, cambium is present between phloem and xylem. So vascular bundles can form secondary xylem and phloem tissues. E.g. dicotyledonous stems.
2. Closed type: In this, cambium is absent. Hence, they do not form secondary tissues. E.g. monocotyledons.
Q 8: Assertion (A): Alimentary canal of frog is short.
Reason (R): Frogs are carnivores and hence the length of intestine is reduced.
Reason (R): Frogs are carnivores and hence the length of intestine is reduced.
(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) A is false but R is true
✅ (1) Both A and R are true and R is the correct explanation of A
▶️ Digestive system of frog consists of alimentary canal and digestive glands.
▶️ Alimentary canal is short because frogs are carnivores and hence the length of intestine is reduced.
▶️ Mouth → buccal cavity → pharynx → oesophagus → stomach → intestine → rectum → cloaca.
Q 9: Assertion (A): In cell membrane, the non-polar tail of saturated hydrocarbons is protected from the aqueous environment.
Reason (R): Lipids have inner polar head and the outer hydrophobic tails.
Reason (R): Lipids have inner polar head and the outer hydrophobic tails.
(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) A is false but R is true
✅ (3) A is true but R is false
▶️ Chemical studies on human RBC show that cell membrane is composed of a lipid bilayer, protein & carbohydrate.
▶️ Lipids (mainly phosphoglycerides) have outer polar head and the inner hydrophobic tails. So the non-polar tail of saturated hydrocarbons is protected from the aqueous environment.
Q 10: Assertion (A): At high temperature, enzymes get destroyed.
Reason (R): Generally, proteins are temporarily inactive by heat.
Reason (R): Generally, proteins are temporarily inactive by heat.
(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) A is false but R is true
✅ (3) A is true but R is false
▶️ Enzymes show highest activity at optimum temperature & pH. Activity declines below and above optimum value.
▶️ At low temperature, enzyme temporarily inactive.
▶️ At high temperature, enzymes get destroyed because proteins are denatured by heat.
▶️ Inorganic catalysts work at high temperature & pressure. But enzymes get damaged at high temperature (> 40° C).
▶️ Thermophilic organisms have enzymes which are stable at high temperature (up to 80-90° C).
Q 11: Assertion (A): Mitosis is also called as equational division.
Reason (R): In mitosis, the number of chromosomes in the parent and progeny cells is same.
Reason (R): In mitosis, the number of chromosomes in the parent and progeny cells is same.
(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) A is false but R is true
✅ (1) Both A and R are true and R is the correct explanation of A
▶️ Mitosis is the cell division occurring in somatic cells.
▶️ It is also called as equational division as the number of chromosomes in the parent and progeny cells is same.
▶️ Mitosis is generally seen in diploid cells. It also occurs in haploid cells of some lower plants and some social insects.
Q 12: Assertion (A): In C4 plants, productivity and yields are better as compared to C3 plants.
Reason (R): In C4 plants, photorespiration is present.
Reason (R): In C4 plants, photorespiration is present.
(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) A is false but R is true
✅ (3) A is true but R is false
▶️ In C4 plants, photorespiration does not occur because they can increase CO2 concentration at the enzyme site. This takes place when C4 acid from the mesophyll is broken down in the bundle cells to release CO2. This minimises the oxygenase activity of RuBisCO.
▶️ Due to the lack of photorespiration, productivity and yields are better in C4 plants. Also, they show tolerance to higher temperatures.
Q 13: Assertion (A): Plants don’t need specialized respiratory organs.
Reason (R): Leaves are adapted for maximum gas exchange during photosynthesis, and most living cells contact with air.
Reason (R): Leaves are adapted for maximum gas exchange during photosynthesis, and most living cells contact with air.
(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) A is false but R is true
✅ (1) Both A and R are true and R is the correct explanation of A
Plants need no specialized respiratory organs because
▪️ Each plant part takes care of its own gas-exchange needs. So gas transport is very limited.
▪️ Very low gas exchange as compared to that of animals.
▪️ Leaves are adapted for maximum gas exchange during photosynthesis. During this, O2 is released within the cell.
▪️ Most living cells contact with air. They are seen close to plant surface. They also have lenticels.
Q 14: Assertion (A): Plant growth is indeterminate and so continues throughout the life.
Reason (R): Plants are autotrophic, allowing them to produce their own food through photosynthesis and store energy in various forms.
Reason (R): Plants are autotrophic, allowing them to produce their own food through photosynthesis and store energy in various forms.
(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) A is false but R is true
✅ (2) Both A and R are true but R is NOT the correct explanation of A
▶️ Plant growth continues throughout the life due to the presence of meristems.
▶️ Meristematic cells have capacity to divide & self-perpetuate.
▶️ The growth where new cells are always added to the plant body by the meristem is called open form of growth.
Q 15: Assertion (A): Oxygen has a significant role in the regulation of respiratory rhythm.
Reason (R): In tissues, PO2 is very high.
Reason (R): In tissues, PO2 is very high.
(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
▶️ Role of oxygen in the regulation of respiratory rhythm is quite insignificant.
▶️ In tissues, PO2 is low and PCO2 is high.
Q 16: Assertion (A): During each cardiac cycle, 2 sounds lub and dub are produced.
Reason (R): Lub is due to the closure of tricuspid and bicuspid valves. Dub is due to the closure of the semilunar valves.
Reason (R): Lub is due to the closure of tricuspid and bicuspid valves. Dub is due to the closure of the semilunar valves.
(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) A is false but R is true
✅ (1) Both A and R are true and R is the correct explanation of A
▶️ Heart sounds: During each cardiac cycle, 2 sounds are produced.
▶️ First sound (lub) is due to the closure of tricuspid and bicuspid valves.
▶️ Second sound (dub) is due to the closure of the semilunar valves.
▶️ One heartbeat = a lub + a dub.
Q 17: Assertion (A): Henle's loop and vasa recta play a crucial role in urine concentration.
Reason (R): Due to their counter-current mechanism, osmolarity increases from the inner medullary interstitium to the cortex.
Reason (R): Due to their counter-current mechanism, osmolarity increases from the inner medullary interstitium to the cortex.
(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) A is false but R is true
✅ (3) A is true but R is false
Mechanism of concentration of the filtrate
▶️ Henle’s loop & vasa recta help to concentrate the urine.
▶️ The flow of filtrate in the 2 limbs of Henle’s loop and the flow of blood through the 2 limbs of vasa recta are in opposite directions (counter current pattern). This is called Counter current mechanism.
▶️ Due to the counter current and proximity between Henle’s loop & vasa recta, osmolarity increases from cortex (300 mOsmolL-1) to the inner medullary interstitium (1200 mOsmolL-1). This gradient is caused by NaCl & urea.
Q 18: Assertion (A): Each myofibril has alternate dark (Anisotropic or A-band) and light striations (Isotropic or I-band).
Reason (R): I-bands contain actin and myosin whereas A-bands contain actin only.
Reason (R): I-bands contain actin and myosin whereas A-bands contain actin only.
(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) A is false but R is true
✅ (3) A is true but R is false
▶️ Each muscle fibre contains myofilaments (myofibrils).
▶️ Each myofibril has alternate dark (Anisotropic or A-band) and light striations (Isotropic or I-band). This is due to the presence of 2 fibrous contractile proteins- thin Actin filament and thick Myosin filament.
▶️ I-bands contain actin. A-bands contain actin and myosin. They are arranged parallel to each other.
Q 19: Assertion (A): Outer part of cerebrum is formed of gray matter.
Reason (R): Cerebral cortex has convulsions & depressions.
Reason (R): Cerebral cortex has convulsions & depressions.
(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) A is false but R is true
✅ (2) Both A and R are true but R is NOT the correct explanation of A
▶️ Outer part of cerebrum is called cerebral cortex. It has convulsions & depressions and is formed of gray matter. Gray colour is due to the presence of neuron cell bodies.
▶️ Inner part of cerebrum is formed of white matter.
Q 20: Assertion (A): Abnormal increase of thyroid hormones resulting in adverse effects on the physiological activities is called Hyperthyroidism.
Reason (R): It is caused due to development of the nodules or the cancer of thyroid gland.
Reason (R): It is caused due to development of the nodules or the cancer of thyroid gland.
(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) A is false but R is true
✅ (1) Both A and R are true and R is the correct explanation of A
▶️ Hyperthyroidism: Abnormal increase of thyroid hormones resulting in adverse effects on the physiological activities.
▶️ It is caused due to development of the nodules or the cancer of thyroid gland.
▶️ Exophthalmic goiter (Grave’s disease): It is a form of Hyperthyroidism. Symptoms are enlargement of thyroid gland, protruded eyeballs, increased BMR & weight loss.