Biology— Concepts, Formulas & Shortcuts
- Mitochondrion is the powerhouse of the cell; chloroplast performs photosynthesis; ribosome makes protein.
- Vitamin deficiencies: A → night blindness, B1 → beriberi, C → scurvy, D → rickets, K → poor clotting.
- The human heart has four chambers: two atria and two ventricles.
- The nephron is the functional unit of the kidney; the neuron is that of the nervous system.
- Insulin (from the pancreas) lowers blood glucose; glucagon raises it.
- Skin is the largest organ; the liver is the largest internal organ and gland.
Biology Practice Questions with Answers
Attempt each question first, then open the explanation. All 16 questions below are free to read and require no signup.
Q1.The "powerhouse of the cell" is the:
Easy- ANucleus
- BRibosome
- CMitochondrion
- DGolgi body
Biology question 1 of 16+Show Answer & Explanation
Answer: C. Mitochondrion
Explanation: Mitochondria generate most of the cell's ATP through oxidative phosphorylation.
Q2.Deficiency of vitamin C causes:
Easy- ARickets
- BScurvy
- CBeriberi
- DNight blindness
Biology question 2 of 16+Show Answer & Explanation
Answer: B. Scurvy
Explanation: Vitamin C is required for collagen synthesis; its deficiency causes scurvy.
Q3.The largest organ of the human body is the:
Easy- ALiver
- BBrain
- CSkin
- DLungs
Biology question 3 of 16+Show Answer & Explanation
Answer: C. Skin
Explanation: Skin is the largest organ overall; the liver is the largest internal organ.
Q4.Which blood group is known as the universal donor?
Moderate- AA positive
- BAB positive
- CO negative
- DB negative
Biology question 4 of 16+Show Answer & Explanation
Answer: C. O negative
Explanation: O negative red cells carry neither A/B antigens nor the Rh D antigen, so they can be given to almost anyone.
Q5.Photosynthesis in plants takes place in the:
Easy- AMitochondrion
- BChloroplast
- CNucleus
- DVacuole
Biology question 5 of 16+Show Answer & Explanation
Answer: B. Chloroplast
Explanation: Chloroplasts contain chlorophyll, which captures light energy to make glucose.
Q6.The human heart has how many chambers?
Easy- ATwo
- BThree
- CFour
- DFive
Biology question 6 of 16+Show Answer & Explanation
Answer: C. Four
Explanation: Two atria and two ventricles, keeping oxygenated and deoxygenated blood fully separated.
Q7.Insulin is produced by the:
Easy- ALiver
- BPancreas
- CThyroid
- DAdrenal gland
Biology question 7 of 16+Show Answer & Explanation
Answer: B. Pancreas
Explanation: The beta cells of the islets of Langerhans in the pancreas secrete insulin, which lowers blood glucose.
Q8.Which part of the brain controls balance and coordination?
Moderate- ACerebrum
- BCerebellum
- CMedulla oblongata
- DHypothalamus
Biology question 8 of 16+Show Answer & Explanation
Answer: B. Cerebellum
Explanation: The cerebellum coordinates voluntary movement and maintains posture and balance.
Q9.The basic structural unit of all living organisms is the:
Easy- ATissue
- BCell
- COrgan
- DMolecule
Biology question 9 of 16+Show Answer & Explanation
Answer: B. Cell
Explanation: The cell is the smallest unit capable of independent life.
Q10.Which blood cells help in clotting?
Easy- ARed blood cells
- BWhite blood cells
- CPlatelets
- DPlasma
Biology question 10 of 16+Show Answer & Explanation
Answer: C. Platelets
Explanation: Platelets aggregate at a wound and trigger the clotting cascade.
Q11.The green pigment in plants responsible for photosynthesis is:
Easy- AHaemoglobin
- BChlorophyll
- CCarotene
- DMelanin
Biology question 11 of 16+Show Answer & Explanation
Answer: B. Chlorophyll
Explanation: Chlorophyll absorbs light energy, chiefly in the red and blue wavelengths.
Q12.Which organ produces bile in the human body?
Moderate- APancreas
- BLiver
- CStomach
- DKidney
Biology question 12 of 16+Show Answer & Explanation
Answer: B. Liver
Explanation: The liver produces bile, which is stored in the gall bladder and aids fat digestion.
Q13.How many bones are there in an adult human body?
Moderate- A186
- B196
- C206
- D216
Biology question 13 of 16+Show Answer & Explanation
Answer: C. 206
Explanation: An adult skeleton has 206 bones, fewer than a newborn's because some fuse during growth.
Q14.Which part of the plant conducts water from the roots?
Moderate- APhloem
- BXylem
- CCambium
- DCortex
Biology question 14 of 16+Show Answer & Explanation
Answer: B. Xylem
Explanation: Xylem carries water and minerals upward; phloem transports food.
Q15.Deficiency of iron in the human body causes:
Easy- ARickets
- BAnaemia
- CGoitre
- DScurvy
Biology question 15 of 16+Show Answer & Explanation
Answer: B. Anaemia
Explanation: Iron is needed for haemoglobin, so its deficiency causes anaemia.
Q16.The functional unit of the nervous system is the:
Easy- ANephron
- BNeuron
- CAlveolus
- DAxon
Biology question 16 of 16+Show Answer & Explanation
Answer: B. Neuron
Explanation: The neuron is the basic signalling cell of the nervous system.
Biology — Frequently Asked Questions
Which vitamin deficiency causes scurvy?+
Vitamin C (ascorbic acid). It impairs collagen synthesis, causing bleeding gums, slow wound healing and joint pain — historically common among sailors without fresh fruit.
Why is the mitochondrion called the powerhouse of the cell?+
Because it carries out oxidative phosphorylation, producing most of the cell's ATP — the energy currency that drives cellular work.
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