BPSC CCE Prelims
Biology Previous Year Questions (PYQs)

Detailed Explanation:

❌ Statement 1 – Incorrect: Muscles can only pull the bone, not push; they work by contraction (pulling) and cannot actively push.
✅ Statement 2 – Correct: Muscles work in antagonistic pairs (e.g., biceps and triceps) – when one contracts (pulls), the other relaxes.
✅ Statement 3 – Correct: During contraction, muscle fibers become shorter, stiffer, and thicker as actin and myosin filaments slide over each other.

Detailed Explanation:

Stomatal opening and closing is regulated by the turgor pressure in guard cells.

When guard cells absorb water, they become turgid and the stomata open; when they lose water, they become flaccid and the stomata close.

✅ Option 3 – Correct: The amount of water in cells directly controls the opening and closing of stomata through changes in turgor pressure.
❌ Option 1 – Incorrect: Position of nucleus does not affect stomatal movement.
❌ Option 2 – Incorrect: While proteins are involved in water transport mechanisms, the immediate cause is water content, not protein composition change.

Detailed Explanation:

Chlorophyll is the green pigment in plants that absorbs red and blue wavelengths of sunlight most effectively for photosynthesis.

Green light is reflected (not absorbed), which is why plants appear green to our eyes.

Detailed Explanation:

✅ Statement 1 – Correct: Petiole is the stalk that attaches the leaf blade to the stem.
❌ Statement 2 – Incorrect: Trees have thick, hard stems with branching near the top, not near the base; shrubs have branching near the base.
✅ Statement 3 – Correct: Creepers have weak stems that cannot stand upright and grow along the ground (e.g., pumpkin, watermelon).

Detailed Explanation:

Transpiration is the primary mechanism responsible for the upward movement of water in tall trees.

Transpiration creates a negative pressure (suction pull) at the top of the plant as water evaporates from leaf stomata, pulling the entire water column upward through xylem vessels via cohesion-tension theory.

While evaporation occurs from leaf surfaces, it is specifically the transpiration process (evaporation through stomata) that generates the pulling force; absorption by roots is passive and responds to this pull rather than creating it.

Detailed Explanation:

Chloroplasts are semi-autonomous organelles capable of self-replication because they contain their own genetic material – both circular DNA (similar to prokaryotes) and RNA (including ribosomal RNA, transfer RNA, and messenger RNA).

The presence of both DNA and RNA enables chloroplasts to synthesize their own proteins and replicate independently within the cell, a characteristic shared with mitochondria that supports the endosymbiotic theory of their evolutionary origin.

Detailed Explanation:

Halophytes are plants specially adapted to survive in high-salt environments, tolerating concentrations up to 1M NaCl. Common examples include mangroves and salt marsh vegetation.

Xerophytes thrive in dry/desert conditions, Mesophytes in moderate environments, and Glycophytes are salt-sensitive plants that cannot tolerate saline conditions.

Therefore, salt-loving plants are Halophytes, making Option 3 the correct answer.

Detailed Explanation:

Fungi are heterotrophic organisms that lack chlorophyll, the pigment essential for photosynthesis. Without chlorophyll, they cannot synthesize their own food from sunlight and must absorb nutrients from organic matter in their environment.

They require oxygen (most are aerobic), utilize carbon dioxide in respiration, and grow in various light conditions—thus these components are not lacking. Their cell walls contain chitin, distinguishing them from true plants.

Therefore, chlorophyll is the key component fungi lack, making Option 2 the correct answer.

Detailed Explanation:

Pollination is precisely defined as the transfer of pollen grains from the anther (male part) to the stigma (female part) of a flower. This is the actual act of pollination, distinct from subsequent reproductive processes.

Germination of pollen grains and growth of the pollen tube occur after pollination is complete. Insect visitation is merely a mechanism (agent) of pollination, not the process itself.

Therefore, the transfer of pollen grain from anther to stigma is the correct definition, making Option 4 the correct answer.

Detailed Explanation:

Soil is the primary source of essential mineral nutrients for plants, including nitrogen, phosphorus, potassium, calcium, magnesium, and micronutrients like zinc and iron. These nutrients are absorbed by roots in ionic forms dissolved in soil water.

The atmosphere provides carbon dioxide for photosynthesis, and light drives photosynthesis, but neither supplies mineral nutrients. Chlorophyll is a pigment that captures light energy, not a nutrient source.

Therefore, soil is the main nutrient reservoir for plants, making Option 3 the correct answer.

Detailed Explanation:

Chloroquine is an antimalarial drug used for treatment and prophylaxis of malaria, making this pair correctly matched.

Tuberculosis is prevented by BCG vaccine (not ATS); Tetanus is prevented by tetanus toxoid (not BCG); Scurvy results from vitamin C deficiency (not thiamine/vitamin B1).

Therefore, only Malaria-Chloroquine is correctly matched, making Option 3 the correct answer.

Detailed Explanation:

Earthworms lack red blood cells (RBCs); their respiratory pigment hemoglobin is dissolved directly in the plasma, not packed inside cells.

Snakes and peacocks are vertebrates that possess RBCs containing hemoglobin for oxygen transport.

Therefore, only earthworm is without red blood cells, making Option 1 the correct answer.

Detailed Explanation:

Carbohydrates are broken down during digestion into their simplest absorbable form, glucose, which is a monosaccharide. All complex carbohydrates (polysaccharides like starch) and disaccharides (like maltose, sucrose) are ultimately degraded to glucose for cellular absorption and energy production.

Glycerol is derived from lipid metabolism, maltose is a disaccharide that further splits into two glucose molecules, and amino acids are the end products of protein digestion.

Therefore, glucose is the ultimate degradation product of carbohydrates, making Option 2 the correct answer.

Detailed Explanation:

Enzymes are biological catalysts that accelerate chemical reactions in living organisms, and the vast majority are proteins. They possess specific three-dimensional structures formed by amino acid chains, enabling them to bind substrates and facilitate reactions.

While a few enzymes are ribozymes (RNA-based), over 99% of all known enzymes are proteinaceous. Lipids, acids, and alkalis serve other biological functions but do not constitute enzyme structure.

Therefore, proteins form the structural basis of most enzymes, making Option 4 the correct answer.

Detailed Explanation:

Edward Jenner performed the first successful vaccination in 1796 using cowpox material to immunize against smallpox, earning him the title Father of Immunology. Robert Koch discovered TB and cholera bacteria; Elie Metchnikoff pioneered immunity research; Joseph Lister introduced antiseptic surgery—none attempted the first vaccination. Therefore, Option 3 is the correct answer.