This includes Assertion and Reason Type questions from Class 11 Biology chapters.
Q 1: Assertion (A): The binomial nomenclature system is universally accepted.
Reason (R): It helps in avoiding confusion and ensures clear communication in the scientific community.
Reason (R): It helps in avoiding confusion and ensures clear communication in the scientific community.
(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.
✅ (1) Both A and R are true, and R is the correct explanation of A.
▶️️ The binomial nomenclature system was introduced by Carl Linnaeus.
▶️️ It assigns a unique two-part Latin name to each species. The first part is the genus name, and the second part is the specific epithet.
▶️️ This system helps avoid confusion and ensures clear communication in the scientific community, as each species has a unique name that is recognized worldwide.
Q 2: Assertion (A): Viruses are considered as living organism.
Reason (R): Even though they cannot exist independently, they have very simple, cellular structure.
Reason (R): Even though they cannot exist independently, they have very simple, cellular structure.
(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.
▶️️ Viruses are non-cellular and not truly ‘living’. So they are not included in five-kingdom classification.
▶️️ Viruses have an inert crystalline structure outside the cell.
▶️️ Viruses are obligate parasites.
▶️️ When they infect a cell, they take over the machinery of the host cell to replicate themselves, killing the host.
Q 3: Assertion (A): Bryophytes are often referred to as amphibians of the plant kingdom.
Reason (R): Bryophytes require water for sexual reproduction and are adapted to both aquatic and terrestrial habitats.
Reason (R): Bryophytes require water for sexual reproduction and are adapted to both aquatic and terrestrial habitats.
(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.
✅ (1) Both A and R are true, and R is the correct explanation of A.
▶️️ Bryophytes occur in damp, humid and shaded localities.
▶️️ Their body is thallus-like and prostrate or erect, and attached to the substratum by unicellular or multicellular rhizoids.
▶️️ They lack true roots, stem or leaves. They may possess root-like, leaf-like or stem-like structures.
▶️️ The main plant body is haploid. It produces gametes, hence is called a gametophyte.
Q 4: Assertion (A): Sponges have Cellular level of organization.
Reason (R): They are unicellular organisms without tissues and organs.
Reason (R): They are unicellular organisms without tissues and organs.
(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.
✅ (3) A is true, but R is false.
▶️️ Sponges (Phylum Porifera) are multicellular organisms with Cellular level of organization, i.e., the cells are arranged as loose cell aggregates. They have no tissues or organs.
Q 5: Assertion (A): Arthropoda is the largest phylum in the animal kingdom.
Reason (R): Arthropods exhibit a high degree of morphological diversity and occupy various ecological niches.
Reason (R): Arthropods exhibit a high degree of morphological diversity and occupy various ecological niches.
(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.
✅ (1) Both A and R are true, and R is the correct explanation of A.
▶️️ Arthropoda is the largest phylum. Over two-thirds of all named species are arthropods.
▶️️ Spider, Scorpion, Crab, Prawn, all insects etc. belong to this phylum.
▶️️ They have jointed appendages.
▶️️ Body is covered by chitinous cuticle (exoskeleton).
Q 6: Assertion (A): Sun flower has Opposite phyllotaxy.
Reason (R): In Sun flower, a pair of leaves arise at each node and lie opposite to each other.
Reason (R): In Sun flower, a pair of leaves arise at each node and lie opposite to each other.
(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.
Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. It is 3 types:
1. Alternate: A single leaf arises at each node in alternate manner. E.g. China rose, mustard & sun flower.
2. Opposite: A pair of leaves arise at each node and lie opposite to each other. E.g. Calotropis and guava.
3. Whorled: More than two leaves arise at a node and form a whorl. E.g. Alstonia.
Q 7: Assertion (A): Trichomes are epidermal hairs present on the stem.
Reason (R): They help to prevent water loss due to transpiration.
Reason (R): They help to prevent water loss due to transpiration.
(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.
✅ (1) Both A and R are true, and R is the correct explanation of A.
Epidermal appendages:
1. Root hairs: Unicellular elongations of the epidermal cells. They help to absorb water and minerals from the soil.
2. Trichomes: Epidermal hairs on the stem. They are usually multicellular, branched or unbranched and soft or stiff. They may be secretory. Trichomes help to prevent water loss due to transpiration.
Q 8: Assertion (A): Development of frog is direct.
Reason (R): Frogs start their life cycle as aquatic larvae (tadpoles) and undergo transformation into terrestrial adults through metamorphosis.
Reason (R): Frogs start their life cycle as aquatic larvae (tadpoles) and undergo transformation into terrestrial adults through metamorphosis.
(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 correct explanation of A
✅ (3) A is false but R is true
▶️️ Development of frog is indirect which means there will be a larval stage in its life cycle.
▶️️ “Development is direct” means there is no larval stage in the life cycle.
Q 9: Assertion (A): The endoplasmic reticulum (ER) is involved in protein and lipid synthesis.
Reason (R): The rough ER synthesizes proteins, while the smooth ER synthesizes lipids.
Reason (R): The rough ER synthesizes proteins, while the smooth ER synthesizes lipids.
(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 correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
Endoplasmic reticulum (ER) are a network of tiny tubular structures scattered in the cytoplasm. 2 types:
1. Rough endoplasmic reticulum (RER): Bear ribosomes on their surface. RER is frequently observed in the cells actively involved in protein synthesis and secretion.
2. Smooth endoplasmic reticulum (SER): Ribosomes are absent. SER is the major site for synthesis of lipid. It synthesizes lipid-like steroidal hormones in animal cells.
Q 10: Assertion (A): Enzymes are biological catalysts that speed up chemical reactions in living organisms.
Reason (R): Enzymes increase the activation energy required for a chemical reaction, thereby increasing the reaction rate.
Reason (R): Enzymes increase the activation energy required for a chemical reaction, thereby increasing the reaction rate.
(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 correct explanation of A
✅ (2) A is true but R is false
▶️️ Activation energy is the additional energy required to start a chemical reaction.
▶️️ In a biochemical reaction, enzymes lower the activation energy. As a result, speed of the reaction increases.
Q 11: Assertion (A): Meiosis produces four genetically dissimilar cells.
Reason (R): Synapsis, crossing over and disjunction of homologous chromosomes occur in the metaphase of meiosis I.
Reason (R): Synapsis, crossing over and disjunction of homologous chromosomes occur in the metaphase of meiosis I.
(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 correct explanation of A
✅ (2) A is true but R is false
▶️️ Synapsis, crossing over and disjunction of homologous chromosomes occur in the Prophase of meiosis I.
▶️️ Prophase I includes 5 phases: Leptotene, Zygotene, Pachytene, Diplotene & Diakinesis.
▶️️ Synapsis (pairing of homologous chromosomes) occurs during Zygotene.
▶️️ Crossing over (exchange of genetic material between homologous chromosomes) during Pachytene.
▶️️ Disjunction (separation of homologous chromosomes) occurs during Anaphase I.
Q 12: Assertion (A): Transfer of electrons from PS II to PS I and finally downhill to NADP+ forms a zigzag shape and is called Z scheme.
Reason (R): This shape is formed when all the carriers are placed in a sequence on a redox potential scale.
Reason (R): This shape is formed when all the carriers are placed in a sequence on a redox potential scale.
(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 correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
Q 13: Assertion (A): Glycolysis is the same in both aerobic and anaerobic conditions.
Reason (R): Glycolysis doesn’t require oxygen and occurs in the cytoplasm of the cell.
Reason (R): Glycolysis doesn’t require oxygen and occurs in the cytoplasm of the cell.
(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 correct explanation of A
✅ (4) Both A and R are true and R correct explanation of A
▶️️ Glycolysis is the partial oxidation of glucose to 2 molecules of pyruvic acid (C3H4O3) in the absence of O2.
▶️ It occurs in cytoplasm of all living organisms.
▶️ Its scheme was given by Gustav Embden, Otto Meyerhof & J. Parnas. So it is also known as EMP pathway.
▶️ In anaerobes, it is the only process in respiration.
Q 14: Assertion (A): ABA is also called the Stress hormone.
Reason (R): ABA decreases the tolerance of plants to various kinds of stresses.
Reason (R): ABA decreases the tolerance of plants to various kinds of stresses.
(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 correct explanation of A
✅ (2) A is true but R is false
▶️️ Abscisic acid (ABA) increases the tolerance of plants to various kinds of stresses.
Q 15: Assertion (A): Inhalation is a passive process whereas exhalation is an active process.
Reason (R): During breathing, diaphragm and external intercostal muscles contract.
Reason (R): During breathing, diaphragm and external intercostal muscles contract.
(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 correct explanation of A
✅ (3) A is false but R is true
▶️️ Inhalation is an active process whereas exhalation is a passive process.
▶️️ During inhalation, diaphragm and external intercostal muscles contract.
▶️️ During exhalation, diaphragm and external intercostal muscles relax.
Q 16: Assertion (A): Type AB individuals are universal recipients in blood transfusions.
Reason (R): AB blood lacks both anti-A and anti-B antibodies, allowing it to accept transfusions of any blood type without agglutination.
Reason (R): AB blood lacks both anti-A and anti-B antibodies, allowing it to accept transfusions of any blood type without agglutination.
(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 correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
▶️️ ABO grouping is based on presence or absence of 2 surface antigens (chemicals that induce immune response) on RBCs namely A & B. Similarly, plasma contains 2 antibodies (proteins produced in response to antigens) namely anti-A & anti-B.
▶️️ Antigen A reacts with anti-A. Antigen B reacts with anti-B.
▶️️ If bloods with interactive antigens & antibodies are mixed, it causes clumping (destruction of RBCs).
▶️️ Persons with O Group are called Universal donors because they can donate blood to persons with any other blood group. Persons with AB group are called Universal recipients because they can accept blood from all groups.
Q 17: Assertion (A): Most of the Ammonotelic animals are aquatic.
Reason (R): Ammonia is highly toxic. So, excretion needs excess of water.
Reason (R): Ammonia is highly toxic. So, excretion needs excess of water.
(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 correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
▶️️ Ammonotelism is the process of excretion of NH3.
▶️️ Ammonotelic animals: Aquatic invertebrates, aquatic insects, bony fishes, aquatic amphibians etc.
▶️️ NH3 is highly toxic. So, excretion needs excess of water. NH3 is readily soluble in water and is excreted by diffusion through body surface or gill surfaces (in fishes) as ammonium ions.
Q 18: Assertion (A): Muscle contraction occurs when the thick filaments slide past the thin filaments.
Reason (R): During muscle contraction, myosin heads bind to actin filaments and pull them towards the center of the sarcomere.
Reason (R): During muscle contraction, myosin heads bind to actin filaments and pull them towards the center of the sarcomere.
(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 correct explanation of A
✅ (3) A is false but R is true
▶️️ Sliding filament theory says contraction of a muscle fibre occurs by the sliding of thin filaments over thick filaments.
▶️️ Thin filament means Actin and thick filament means Myosin.
Q 19: Assertion (A): When a stimulus is applied to the resting neuron, the membrane at site A becomes permeable to Na+.
Reason (R): Na-K pump transports 3 Na+ outwards for 2 K+ into the cell.
Reason (R): Na-K pump transports 3 Na+ outwards for 2 K+ into the cell.
(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 correct explanation of A
✅ (1) Both A and R are true but R is NOT the correct explanation of A
▶️️ The Na-K pump helps maintain the resting membrane potential by pumping 3 Na+ ions out of the cell for every 2 K+ ions it pumps in.
▶️️ But the process of the membrane becoming permeable to Na+ when a stimulus is applied, known as depolarization, is a separate process that involves voltage-gated Na+ channels. These channels open in response to a stimulus, allowing Na+ ions to flow into the cell.
Q 20: Assertion (A): Hormone secretion of pituitary gland is under the control of hypothalamus.
Reason (R): Hypothalamus secretes several releasing and inhibiting hormones that influence hormone secretion of pituitary.
Reason (R): Hypothalamus secretes several releasing and inhibiting hormones that influence hormone secretion of pituitary.
(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 correct explanation of A
✅ (4) Both A and R are true and R is the correct explanation of A
Neurosecretory cells (nuclei) of hypothalamus secrete the following types of hormones:
▶️️ Releasing hormones: Stimulate secretion of pituitary hormones. E.g. gonadotropin releasing hormone (GnRH) stimulates pituitary to release gonadotropins (FSH & LH).
▶️️ Inhibiting hormones: Inhibit secretion of pituitary hormones. E.g. Somatostatin inhibits release of growth hormone from pituitary.
▶️️ Oxytocin & vasopressin: These are transported axonally and stored in pituitary.