1,431 practice questions for CBSE Class 11 Biology, organised by NCERT chapter (19 chapters). Every question includes a written explanation. Pick a chapter below, or try the samples first.
Practice by chapter
The Living World
75 questions in timed practice
Biological Classification
80 questions in timed practice
Plant Kingdom
75 questions in timed practice
Animal Kingdom
75 questions in timed practice
Morphology of Flowering Plants
75 questions in timed practice
Anatomy of Flowering Plants
75 questions in timed practice
Structural Organisation in Animals
75 questions in timed practice
Cell: The Unit of Life
75 questions in timed practice
Biomolecules
75 questions in timed practice
Cell Cycle and Cell Division
76 questions in timed practice
Photosynthesis in Higher Plants
75 questions in timed practice
Respiration in Plants
75 questions in timed practice
Plant Growth and Development
75 questions in timed practice
Breathing and Exchange of Gases
75 questions in timed practice
Body Fluids and Circulation
75 questions in timed practice
Excretory Products and their Elimination
75 questions in timed practice
Locomotion and Movement
75 questions in timed practice
Neural Control and Coordination
75 questions in timed practice
Chemical Coordination and Integration
75 questions in timed practice
Sample questions
Q1
hard
The appendicular skeleton has 126 bones in total. A student is given: pectoral girdle = 4 bones, pelvic girdle = 2 bones, one forelimb, including its carpals, metacarpals and phalanges, = 30 bones, and one hindlimb, including the kneecap, tarsals, metatarsals and phalanges, = 30 bones. Using two forelimbs and two hindlimbs, does this account for all 126 bones, and if not, how many are missing?
AYes, it accounts for exactly 126 bones
BNo, 8 bones are missing, because the kneecaps and wrist bones must be counted again
CNo, 6 bones are missing, since each girdle must be counted twice
DNo, 4 bones are missing
Show answer and explanation
Correct answer: A - Yes, it accounts for exactly 126 bones
Adding the girdles, $4+2=6$, to two forelimbs and two hindlimbs at 30 bones each, $4\times30=120$, gives $6+120=126$, which exactly accounts for the appendicular skeleton's total. The girdle counts already cover both sides of the body, and the kneecaps and wrist bones are already inside the limb counts, so nothing needs to be counted again and no bones are missing.
Q2
easy
What happens during anaphase II of meiosis?
AHomologous chromosomes pair up along their entire length
BThe DNA of the cell is replicated for a second time
CThe centromeres split and the sister chromatids move to opposite poles
DHomologous chromosomes separate and move to opposite poles
Show answer and explanation
Correct answer: C - The centromeres split and the sister chromatids move to opposite poles
Anaphase II is like a mitotic anaphase: each centromere splits and the two sister chromatids are pulled to opposite poles as separate chromosomes. Homologues separated earlier, in anaphase I, and no homologous pairs are left in the cell by meiosis II. Pairing of homologues took place in zygotene of prophase I. There is no DNA replication between the two meiotic divisions.
Q3
medium
When guard cells take up water and become turgid, the stomatal pore between them opens. What structural feature of the guard cell wall makes this possible?
AThe wall bordering the pore is thicker than the outer wall, so the cell bows outward as it swells, pulling the pore open
BThe wall bordering the pore is thinner than the outer wall, causing the cell to collapse inward and seal the pore
CGuard cells have no cell wall, so they change shape freely with any change in water content
DThe wall is uniformly thick all around, so the whole cell simply expands into a sphere
Show answer and explanation
Correct answer: A - The wall bordering the pore is thicker than the outer wall, so the cell bows outward as it swells, pulling the pore open
Because the wall next to the pore is thicker and less stretchable than the outer wall, a turgid guard cell bulges outward more on its outer side, curving away from its partner and opening the pore between them. Uniform thickening would not create this bowing, and reversing which wall is thicker would seal rather than open the pore. Guard cells do have a wall, which is essential to this mechanism.
Q4
medium
Consider the following statements about the head region of a frog.
(I) A pair of external nostrils is present near the tip of the snout.
(II) A pair of large eyes is present, each protected by eyelids and a thin transparent nictitating membrane.
(III) A distinct outer ear flap, similar to a mammal's pinna, projects from the side of the head.
How many of these statements are correct?
AOnly one
BOnly two
CNone
DAll three
Show answer and explanation
Correct answer: B - Only two
Statements I and II are correct, frogs have external nostrils near the snout tip, and eyes protected by eyelids plus a transparent nictitating membrane. Statement III is false, a frog has a flat circular tympanum for sound reception but no projecting outer ear flap like a mammal's pinna.
Q5
medium
A genetically dwarf variety of pea plant, much shorter than the normal tall variety, is sprayed repeatedly with gibberellic acid during its growth. Over time, the treated dwarf plants grow to nearly the same height as untreated tall plants. What does this best demonstrate about gibberellins?
AGibberellins can promote internode elongation strongly enough to overcome a genetic dwarfing condition
BGibberellins have no effect on stem length and only affect flowering time
CGibberellins convert dwarf plants into tall plants permanently by altering their genes
DDwarf pea plants are simply pea plants that have never been treated with any hormone
Show answer and explanation
Correct answer: A - Gibberellins can promote internode elongation strongly enough to overcome a genetic dwarfing condition
Applying gibberellic acid to genetically dwarf pea plants is a classic demonstration that gibberellins promote internode elongation strongly enough to make them approach normal tall height. This is a physiological effect of the applied hormone, not a change to the plant's genes, so it is not a permanent genetic conversion. The result directly shows an effect on stem length, contradicting the claim of no effect. All pea plants, dwarf or tall, produce their own hormones; the dwarf condition here is genetic, not simply an absence of any hormone.
Q6
medium
The hypothalamus sits at the base of the brain, just above the pituitary gland. Which statement correctly describes its relationship with the pituitary?
AIt lies inside the posterior pituitary and secretes anterior pituitary hormones such as growth hormone directly into the blood
BIt produces releasing and inhibiting hormones that control anterior pituitary secretions, and also sends nerve fibres into the posterior pituitary
CIt has no vascular or neural connection to the pituitary, and the two glands work entirely independently, each responding to blood hormone levels on its own
DIt controls only the posterior pituitary and has no influence on the anterior pituitary
Show answer and explanation
Correct answer: B - It produces releasing and inhibiting hormones that control anterior pituitary secretions, and also sends nerve fibres into the posterior pituitary
The hypothalamus secretes releasing hormones, which stimulate, and inhibiting hormones, which suppress, anterior pituitary secretions, and separately sends nerve fibres into the posterior pituitary that carry oxytocin and vasopressin for release. It is not located inside the posterior pituitary, and it influences both pituitary lobes, not just one.
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