100 Biology MCQs with Answers and Explanations for Army, Navy and PAF Tests

1What is the basic unit of life?

1. Tissue
2. Cell
3. Organ
4. Nucleus

2Who discovered the cell?

1. Charles Darwin
2. Robert Hooke
3. Louis Pasteur
4. Gregor Mendel

3Which organelle is known as the powerhouse of the cell?

1. Nucleus
2. Ribosome
3. Mitochondrion
4. Golgi apparatus

4Which organelle controls most cell activities?

1. Nucleus
2. Vacuole
3. Lysosome
4. Cell wall

5Which structure controls the movement of substances into and out of a cell?

1. Cell membrane
2. Nucleus
3. Ribosome
4. Chromosome

6Which organelle is responsible for protein synthesis?

1. Lysosome
2. Ribosome
3. Vacuole
4. Centriole

7Which structure is present in plant cells but absent in animal cells?

1. Cell membrane
2. Cytoplasm
3. Cell wall
4. Nucleus

8Which pigment gives plants their green colour?

1. Haemoglobin
2. Chlorophyll
3. Melanin
4. Keratin

9Where does photosynthesis mainly occur in plant cells?

1. Mitochondria
2. Chloroplasts
3. Ribosomes
4. Nucleus

10What is the jelly-like substance inside a cell called?

1. Cytoplasm
2. Cell wall
3. Chromosome
4. Tissue

11What is the study of living organisms called?

1. Geology
2. Biology
3. Astronomy
4. Ecology only

12What is the study of plants called?

1. Zoology
2. Botany
3. Anatomy
4. Physiology

13What is the study of animals called?

1. Botany
2. Genetics
3. Zoology
4. Microbiology

14What is the study of microorganisms called?

1. Microbiology
2. Ecology
3. Taxonomy
4. Anatomy

15What is the study of heredity called?

1. Ecology
2. Genetics
3. Physiology
4. Embryology

16Which molecule carries hereditary information in most living organisms?

1. DNA
2. Glucose
3. Starch
4. Water

17What does DNA stand for?

1. Deoxyribonucleic acid
2. Dinucleic acid
3. Deoxyribose nitrogen acid
4. Double nucleic arrangement

18Where are chromosomes mainly located in a human cell?

1. Cell membrane
2. Nucleus
3. Cytoplasm only
4. Ribosome

19How many chromosomes are present in a normal human body cell?

1. 23
2. 44
3. 46
4. 48

20How many pairs of chromosomes are present in a normal human body cell?

1. 22
2. 23
3. 44
4. 46

21Which organ pumps blood throughout the human body?

1. Liver
2. Heart
3. Lungs
4. Kidney

22How many chambers does the human heart have?

1. Two
2. Three
3. Four
4. Five

23Which blood cells transport oxygen?

1. White blood cells
2. Red blood cells
3. Platelets
4. Plasma cells

24Which component of blood helps fight infections?

1. Red blood cells
2. White blood cells
3. Platelets
4. Plasma only

25Which component of blood helps in clotting?

1. Platelets
2. Red blood cells
3. Neurons
4. Alveoli

26What is the liquid part of blood called?

1. Lymph
2. Plasma
3. Haemoglobin
4. Cytoplasm

27Which blood group is considered the universal red-cell donor when Rh factor is included?

1. AB positive
2. A positive
3. O negative
4. B negative

28Which blood group is considered the universal red-cell recipient when Rh factor is included?

1. O negative
2. AB positive
3. A negative
4. B positive

29Which blood vessels carry blood away from the heart?

1. Veins
2. Arteries
3. Capillaries only
4. Lymph vessels

30Which blood vessels usually carry blood toward the heart?

1. Arteries
2. Veins
3. Bronchi
4. Nerves

31Which organ is primarily responsible for breathing?

1. Stomach
2. Lungs
3. Liver
4. Pancreas

32What is the functional unit of the lungs where gas exchange occurs?

1. Nephron
2. Alveolus
3. Neuron
4. Villus

33Which gas do humans take in for cellular respiration?

1. Carbon dioxide
2. Oxygen
3. Nitrogen
4. Hydrogen

34Which gas is removed from the body during exhalation?

1. Carbon dioxide
2. Helium
3. Hydrogen
4. Neon

35Which organ filters waste from the blood and produces urine?

1. Heart
2. Kidney
3. Stomach
4. Spleen

36What is the functional unit of the kidney?

1. Neuron
2. Nephron
3. Alveolus
4. Villus

37Which organ produces bile?

1. Pancreas
2. Liver
3. Kidney
4. Small intestine

38Where is bile stored before release into the small intestine?

1. Stomach
2. Gallbladder
3. Pancreas
4. Appendix

39Which organ produces insulin?

1. Liver
2. Pancreas
3. Kidney
4. Spleen

40Which hormone helps lower blood glucose levels?

1. Adrenaline
2. Insulin
3. Thyroxine
4. Melatonin

41Which organ begins the digestion of starch?

1. Mouth
2. Large intestine
3. Liver
4. Oesophagus

42Which acid is present in the human stomach?

1. Acetic acid
2. Hydrochloric acid
3. Sulfuric acid
4. Nitric acid

43In which part of the digestive system are most nutrients absorbed?

1. Stomach
2. Small intestine
3. Large intestine
4. Oesophagus

44What is the main function of the large intestine?

1. Pumping blood
2. Absorbing water and forming faeces
3. Producing insulin
4. Filtering blood

45Which enzyme in saliva begins starch digestion?

1. Pepsin
2. Amylase
3. Lipase
4. Trypsin

46Which nutrient is the body’s main immediate source of energy?

1. Carbohydrates
2. Vitamins
3. Minerals
4. Water

47Which nutrient is essential for growth and tissue repair?

1. Proteins
2. Water only
3. Fibre only
4. Minerals only

48Which vitamins are fat-soluble?

1. B and C
2. A, D, E and K
3. B and K only
4. C and D only

49Which vitamin is produced in the skin with the help of sunlight?

1. Vitamin A
2. Vitamin B12
3. Vitamin C
4. Vitamin D

50Deficiency of vitamin C causes which disease?

1. Rickets
2. Scurvy
3. Night blindness
4. Beriberi

51Deficiency of vitamin D in children can cause which disease?

1. Scurvy
2. Rickets
3. Pellagra
4. Anaemia

52Deficiency of vitamin A can cause which problem?

1. Night blindness
2. Scurvy
3. Rickets
4. Goitre

53Which mineral is essential for haemoglobin formation?

1. Calcium
2. Iron
3. Sodium
4. Iodine

54Which mineral is important for strong bones and teeth?

1. Calcium
2. Chlorine
3. Sodium
4. Copper only

55Which gland is commonly called the master gland?

1. Thyroid
2. Pituitary
3. Adrenal
4. Pineal

56Which gland produces thyroxine?

1. Thyroid
2. Pancreas
3. Pituitary
4. Adrenal

57Which hormone is commonly associated with the body’s fight-or-flight response?

1. Insulin
2. Adrenaline
3. Oestrogen
4. Melatonin

58Which part of the brain helps maintain balance and coordination?

1. Cerebellum
2. Medulla
3. Hypothalamus
4. Cerebrum only

59Which part of the brain controls many involuntary activities such as breathing?

1. Cerebellum
2. Medulla oblongata
3. Cerebrum
4. Occipital lobe

60What is the basic functional unit of the nervous system?

1. Nephron
2. Neuron
3. Alveolus
4. Platelet

61Which organ is responsible for hearing and balance?

1. Eye
2. Ear
3. Nose
4. Tongue

62Which part of the eye controls the amount of light entering?

1. Retina
2. Iris
3. Cornea only
4. Optic nerve

63Which part of the eye contains light-sensitive cells?

1. Retina
2. Iris
3. Sclera
4. Eyelid

64Which cells in the retina are especially important for colour vision?

1. Rods
2. Cones
3. Neurons of the spinal cord
4. Platelets

65Which system provides support and protection to the body?

1. Digestive system
2. Skeletal system
3. Endocrine system
4. Excretory system

66How many bones are typically present in an adult human skeleton?

1. 106
2. 206
3. 306
4. 406

67Which is the longest bone in the human body?

1. Humerus
2. Femur
3. Tibia
4. Radius

68Which is the smallest bone in the human body?

1. Stapes
2. Femur
3. Patella
4. Ulna

69Which type of joint is found at the shoulder?

1. Hinge joint
2. Ball-and-socket joint
3. Fixed joint
4. Pivot joint only

70Which type of joint is found at the elbow?

1. Ball-and-socket joint
2. Hinge joint
3. Fixed joint
4. Gliding joint only

71What is the process by which green plants make food using light?

1. Respiration
2. Photosynthesis
3. Transpiration
4. Fermentation

72Which raw materials are used in photosynthesis?

1. Oxygen and glucose
2. Carbon dioxide and water
3. Nitrogen and oxygen
4. Protein and minerals

73Which part of a plant absorbs most water from the soil?

1. Flowers
2. Roots
3. Fruits
4. Leaves only

74Which tissue transports water and minerals from roots to other parts of a plant?

1. Phloem
2. Xylem
3. Epidermis only
4. Cortex only

75Which tissue transports sugars in plants?

1. Xylem
2. Phloem
3. Cork
4. Root hair

76What is the loss of water vapour from plant leaves called?

1. Photosynthesis
2. Transpiration
3. Respiration
4. Germination

77Which part of a flower produces pollen?

1. Stigma
2. Anther
3. Ovary
4. Sepal

78Which part of a flower usually develops into the fruit after fertilisation?

1. Petal
2. Ovary
3. Anther
4. Sepal

79Which part of a plant embryo develops into the root?

1. Plumule
2. Radicle
3. Cotyledon
4. Petal

80What is the process by which a seed begins to grow called?

1. Pollination
2. Germination
3. Transpiration
4. Fertilisation

81Which organisms are known as decomposers in many ecosystems?

1. Fungi and bacteria
2. Lions and tigers
3. Birds only
4. Green plants only

82What is an organism that makes its own food called?

1. Consumer
2. Producer
3. Parasite
4. Predator

83Which organisms are called consumers in a food chain?

1. Organisms that make their own food
2. Organisms that obtain energy by eating other organisms
3. Only green plants
4. Only decomposers

84What is the natural home of an organism called?

1. Habitat
2. Population
3. Community
4. Climate

85What is the study of relationships between organisms and their environment called?

1. Anatomy
2. Ecology
3. Genetics
4. Histology

86Which microorganism is commonly used to make bread rise?

1. Yeast
2. Amoeba
3. Plasmodium
4. Paramecium

87Which microorganism causes malaria?

1. Bacterium
2. Plasmodium
3. Yeast
4. Amoeba proteus

88Which organism causes tuberculosis?

1. Mycobacterium tuberculosis
2. Plasmodium
3. Influenza virus
4. Yeast

89Which type of pathogen causes influenza?

1. Fungus
2. Virus
3. Worm
4. Protozoan

90Which practice helps prevent the spread of many infectious diseases?

1. Sharing used needles
2. Regular handwashing
3. Drinking unsafe water
4. Ignoring food hygiene

91Which process produces two genetically similar daughter cells for growth and repair?

1. Mitosis
2. Meiosis
3. Fertilisation
4. Pollination

92Which type of cell division produces gametes in humans?

1. Mitosis
2. Meiosis
3. Binary fission
4. Budding

93What are the male reproductive cells called?

1. Ova
2. Sperm
3. Zygotes
4. Embryos

94What is the female reproductive cell called?

1. Sperm
2. Ovum
3. Neuron
4. Platelet

95What is the fusion of male and female gametes called?

1. Respiration
2. Fertilisation
3. Germination
4. Transpiration

96Which scientist is known for proposing the theory of evolution by natural selection?

1. Gregor Mendel
2. Charles Darwin
3. Robert Hooke
4. Louis Pasteur

97Which scientist is known as the father of genetics?

1. Charles Darwin
2. Gregor Mendel
3. Alexander Fleming
4. Robert Koch

98Which scientist discovered penicillin?

1. Alexander Fleming
2. Louis Pasteur
3. Edward Jenner
4. Robert Hooke

99Which disease is caused by a deficiency of insulin or ineffective insulin action?

1. Diabetes mellitus
2. Malaria
3. Tuberculosis
4. Scurvy

100What is the main function of vaccines?

1. To replace all white blood cells
2. To train the immune system to recognise specific pathogens
3. To digest food
4. To increase bone length