All Free Biology MCQs with Answers

• A. P 600
• B. P 680
• C. P 700
• D. P 760

Explanation: Photosystem I has chlorophyll a molecule which absorbs maximum light of 700 nm and is called P700, whereas reaction center of photosystem…

• A. Red-Yellow-Green
• B. Red-Orange-Blue
• C. Orange-Blue-Green
• D. Red-Orange-Yellow

Explanation: Accessory Pigments are the source of much of the RED-ORANGE-YELLOW coloration that we see in plant leaves.

• A. Grana
• B. Stroma
• C. Thylakoids
• D. Intergrana

Explanation: In chloroplasts, chemiosmosis occurs in the thylakoids.

• A. Sodium Ions
• B. Magnesium ions
• C. Potassium ions
• D. Calcium ions

Explanation: Influx of potassium ions decreases water potential in the guard cell so water enters the cell from surrounding cells.

• A. RuBP + ATP
• B. RuBP + PGAL
• C. NADPH + ATP
• D. PGAL + ATP

Explanation: The two products of light dependent reaction of photosystem are ATP and NADPH.The light reaction is the first stage of the photosynthesis…

• A. Phytochrome
• B. Phytokinin
• C. Phytocyanin
• D. Carotenoids

Explanation: Some carotenoids protect chlorophyll from intense light by absorbing and dissipating excessive light energy, rather than transferring…

• A. Yellow, Red, Green, Blue
• B. Orange, Yellow, Red, Brown
• C. Green, Yellow, Blue, Brown
• D. Blue, Red, Green, Yellow

Explanation: Photosynthetic organisms contain light-absorbing molecules called pigments that absorb only specific wavelengths of visible light while…

• A. PC
• B. PQ
• C. Cytochrome-b
• D. Pentamerous

Explanation: Plastoquinone (PQ) is the correct answer as it accepts excited electrons from photosystem-II and transfers them down the electron…

• A. Cristae to stroma
• B. Stroma to grana
• C. Grana to cristae
• D. Grana to stroma

Explanation: Photosynthesis occurs in 2 steps:1. Light-dependent reactions2. Light-independent reactionsLight-dependent reactions occur on the…

• A. 4-ATP
• B. 36-ATP
• C. 32-ATP
• D. NO-ATP

Explanation: Photorespiration (also known as the C2 cycle) is a metabolic process in plants where the enzyme rubisco combines O2 with RuBP in the…

• A. PGA
• B. PGAL
• C. RUBP
• D. RUBISCO

Explanation: In the third and final stage of the Calvin cycle i.e. regeneration of RuBP, 1 glyceraldehyde 3-phosphate molecule is used to create…

• A. Thin & elastic
• B. Thick & elastic
• C. Thin & non elastic
• D. Thick & non elastic

Explanation: Guard cells are pairs of specialized epidermal cells that work to control excessive water loss, closing on hot, dry, or windy days and…

• A. Phosphorus
• B. Zinc
• C. Iron
• D. Iodine

Explanation: Calcium, sodium, magnesium, phosphorus and potassium are sometimes included as macronutrients because they are required in relatively…

• A. Iron
• B. Copper
• C. Zinc
• D. Magnesium

Explanation: Magnesium (Mg2+) is an essential macronutrient of living cells and is the second most prevalent free divalent cation in plants.

• A. Macronutrients
• B. Micronutrients
• C. Trace elements
• D. Minor elements

Explanation: Hydrogen, magnesium, nitrogen, and phosphorus all are macronutrients. Macronutrients are the nutrients we need in larger quantities that…

• A. Kidney shape
• B. Oval
• C. Rounded
• D. Dumbbell shaped

Explanation: The correct answer is dumbbell-shaped. Monocots have stomatal guard cells that are dumbbell-shaped, allowing for better regulation of gas…

• A. Glycolate --> Glycine, Glycine --> Serine + CO2, RuBP + O2 --> Glycolate
• B. RuBP + O2 --> Glycolate, Glycine --> Serine + CO2, Glycolate --> Glycine
• C. RuBP + O2 --> Glycolate, Glycolate --> Glycine, Glycine --> Serine + CO2
• D. Glycine --> Serine + CO2, RuBP + O2 --> Glycolate, Glycolate --> Glycine

Explanation: Photorespiration is a process in plants where RuBP (Ribulose Bisphosphate) reacts with oxygen, rather than carbon dioxide, leading to a…

• A. Blue, green, brown, or red
• B. Orange, yellow, blue, or brown
• C. Yellow, orange, red, or brown
• D. Blue, red, orange, or brown

Explanation: Carotenoids are accessory pigments found in plants that include colors such as yellow, orange, red, and brown.

• A. Transportation
• B. Transduction
• C. Translocation
• D. Transformation

Explanation: The correct answer is translocation. This process specifically refers to the movement of organic solutes such as sugars and amino acids…

• A. Zinc (Zn)
• B. Iron (Fe)
• C. Cobalt (Co)
• D. Manganese (Mn)

Explanation: Zinc (Zn) deficiency is directly linked to delayed wound healing because zinc is integral to the processes of collagen synthesis and cell…