Difficult Biology MCQ for Competitive Exams 2025

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Difficult Biology mcq for Competitive Exams. We covered all the Difficult Biology mcq for Competitive Exams in this post for free so that you can practice well for the exam.

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Difficult Biology mcq for Competitive Exams

A Disease caused by a fungus is

a) Filaria

b) Tapeworm

c) Ringworm

d) Roundworm

Option c – Ringworm

Housefly is responsible for spreading

a) Malaria

b) Flu

c) Common cold

d) Typhoid

Option d – Typhoid

Oxygen is transported in the blood with the help of

a) Leucocytes

b) Erythrocytes

c) Thrombocytes

d) Lymphocytes

Option b – Erythrocytes

Chromosomes are made up of

a) DNA and proteins

b) RNA and sugar

c) DNA and lipids

d) RNA and amino Acids

Option a – DNA and proteins

The smallest structural and functional unit of life is

a) Cell

b) Organ

c) Tissue

d) System

Option a – Cell

The absence of fish in a river indicates

a) Zone of recovery

b) Zone of degradation

c) Zone of active decomposition

d) All zones of Pollution

Option b – Zone of degradation

The largest type of white blood cell is

a) Monocyte

b) Erythrocyte

c) Lymphocyte

d) Thrombocyte

Option a – Monocyte

Identify the tapeworm among the following

a) Schistosoma

b) Taenia

c) Fasciola

d) Enterobius

Option b – Taenia

The plant with significant pesticidal properties is

a) Pongamia

b) Jamun

c) Castor

d) Jatropha

Option d – Jatropha

Which of the following is an autotrophic organism

a) Algae

b) Grasshopper

c) Mushroom

d) Butterfly

Option a – Algae

Oxyntic cells secrete

a) Pepsin

b) Lactic Acid

c) Enterokinase

d) Hydrochloric Acid

Option d – Hydrochloric Acid

Cells that are associated with guard cells are called

a) Subsidiary cells

b) Transfusion tissue

c) Hypodermal cells

d) Complementary cells

Option a – Subsidiary cells

The therapy used for treating cancer is

a) Psychotherapy

b) Physiotherapy

c) Chemotherapy

d) Electrotherapy

Option c – Chemotherapy

Which of the following diseases is viral in nature

a) Cholera

b) Poliomyelitis

c) Pneumonia

d) Whooping cough

Option b – Poliomyelitis

The Animal that tolerates Heat better during summer is

a) Cow

b) Goat

c) Donkey

d) Buffalo

Option b – Goat

Nitrogen circulation in the ecosystem is carried out by

a) Bacteria

b) Fungi

c) Protozoa

d) Earthworm

Option a – Bacteria

Identify the non-poisonous snake from the following

a) Python

b) Elapes

c) Dryophic

d) Cobra

Option a – Python

Which of the following is a viral Disease

a) Plague

b) Cholera

c) Mumps

d) Syphilis

Option c – Mumps

Liver is rich in

a) Proteins

b) Sugars

c) Minerals

d) Fat-soluble vitamins

Option a – Proteins

‘Pigeon milk’ is secreted by

a) Crop

b) Mammals

c) Birds

d) All of these

Option c – Birds

Which of the following is the smallest bird?

a) Parrot

b) House sparrow

c) Pigeon

d) Hummingbird

Option d – Hummingbird

Tetanus is caused by –

a) Virus

b) Bacteriophage

c) Salmonella

d) Clostridium

Option d – Clostridium

ECG is used to detect the functioning of –

a) Brain

b) Lung

c) Heart

d) Kidney

Option c – Heart

Angora wool is obtained from –

a) Sheep

b) Goat

c) Rabbit

d) Fox

Option c – Rabbit

Roundworm in humans is usually found in the –

a) Liver

b) Small intestine

c) Large intestine

d) Stomach

Option c – Large intestine

Which organism possesses the highest number of ribs?

a) Snake

b) Flying mammal

c) Ray fish

d) Crocodile

Option a – Snake

Iodoform is commonly used as an –

a) Analgesic

b) Antiseptic

c) Antipyretic

d) Anaesthetic

Option b – Antiseptic

Pulses are a rich source of –

a) Vitamins

b) Fats

c) Carbohydrates

d) Proteins

Option d – Proteins

The primary raw material for producing rayon is –

a) Silicon

b) Nylon

c) Cellulose

d) Radium and Argon

Option c – Cellulose

The term ‘Genetics’ was introduced by –

a) Mendel

b) Bateson

c) Morgan

d) Johansen

Option b – Bateson

During photosynthesis, green plants take in –

a) Nitrogen

b) Oxygen

c) Carbon dioxide

d) Carbon monoxide

Option c – Carbon dioxide

Reserpine is used for –

a) Pain relief

b) Lowering high blood pressure

c) Treating arthritis

d) Increasing blood pressure

Option b – Lowering high blood pressure

Which Animal lacks a nervous system?

a) Tapeworm

b) Snail

c) Leech

d) Amoeba

Option d – Amoeba

The longest bone in the human body is the –

a) Humerus

b) Tibia

c) Ulna

d) Femur

Option d – Femur

Chewing gum is primarily made from –

a) Gum

b) Tannin

c) Latex

d) Resin

Option c – Latex

Which organism is known as the farmer’s friend?

a) Bee

b) Earthworm

c) Ant

d) Butterfly

Option b – Earthworm

Underground fruits are produced by –

a) Carrot

b) Onion

c) Groundnut

d) Potato

Option c – Groundnut

A normal human body cell contains how many chromosomes?

a) 44

b) 46

c) 43

d) 45

Option b – 46

Most plants absorb nitrogen from soil in the form of –

a) Nitric Acid

b) Nitrates

c) Nitrites

d) Free nitrogen gas

Option b – Nitrates

Leprosy is caused by –

a) Virus

b) Germs

c) Fungus

d) Bacteria

Option d – Bacteria

Ranikhet Disease affects –

a) Cow

b) Goat

c) Fowl

d) Horse

Option c – Fowl

AIDS primarily attacks the –

a) Nervous system

b) Respiratory system

c) Immune system

d) Blood circulatory system

Option c – Immune system

The study of plants is known as –

a) Zoology

b) Botany

c) Chemistry

d) Physics

Option c – Chemistry

Which instrument is used to listen to the heartbeat?

a) Thermometer

b) Stethoscope

c) Haemocytometer

d) Electrocardiogram

Option b – Stethoscope

Which one is a viral Disease?

a) Polio

b) TB

c) Cholera

d) Rabies

Option c – Cholera

Insulin is administered to patients suffering from –

a) Malaria

b) Diabetes

c) Smallpox

d) Tuberculosis

Option b – Diabetes

Bronchitis affects the –

a) Liver

b) Intestine

c) Blood

d) Respiratory tract

Option d – Respiratory tract

Trees release which gas during nighttime?

a) Hydrogen

b) Oxygen

c) Carbon dioxide

d) Nitrogen

Option c – Carbon dioxide

Biological death in a person means the death of tissues in the –

a) Brain

b) Kidney

c) Lungs

d) Heart

Option a – Brain

Deficiency of vitamin A results in –

a) Beri-beri

b) Pellagra

c) Rickets

d) Night blindness

Option d – Night blindness

A clone refers to a group of individuals produced by –

a) Hybridisation

b) Self-pollination

c) Micropropagation

d) Cross-pollination

Option c – Micropropagation

Typhoid fever is caused by –

a) Virus

b) Fungi

c) Bacteria

d) Protozoa

Option c – Bacteria

In humans, fat is primarily stored in –

a) Liver

b) Epidermis

c) Epithelium

d) Adipose tissue

Option d – Adipose tissue

The first cloned sheep was named –

a) Jolly

b) Molly

c) Dolly

d) Rolly

Option c – Dolly

Binomial nomenclature was introduced by –

a) John Ray

b) Aristotle

c) Huxley

d) Linnaeus

Option a – John Ray

Cholesterol is not present in –

a) Ice cream

b) Buttermilk

c) Groundnut oil

d) Butter oil

Option c – Groundnut oil

Transcription is the process of producing –

a) RNA

b) DNA

c) Protein

d) Lipids

Option b – DNA

Which chromosomal combination determines maleness in humans?

a) XY

b) XXX

c) XO

d) XX

Option a – XY

Malaria can be treated using a drug derived from –

a) Oak tree

b) Neem tree

c) Belladonna tree

d) Cinchona tree

Option d – Cinchona tree

The strongest bone in the human body is located in the –

a) Jaw

b) Arm

c) Neck

d) Thigh

Option d – Thigh

The human heart beats approximately how many times per minute?

a) 25 times

b) 72 times

c) 30 times

d) 96 times

Option b – 72 times

Which of the following is a female sex hormone?

a) Insulin

b) Oxytocin

c) Androgen

d) Estrogen

Option d – Estrogen

The hormone released in higher amounts during excitement is –

a) Serotonin

b) Cortisone

c) Oestrogen

d) Adrenaline

Option c – Oestrogen

The study of field crops is called –

a) Pomology

b) Floriculture

c) Agronomy

d) Olericulture

Option c – Agronomy

Cancer is characterized by uncontrolled –

a) Cell division

b) Cell swelling

c) Cell deformity

d) Cell inflammation

Option a – Cell division

The part of the cinchona plant used to obtain medicine is –

a) Leaf

b) Bark

c) Pericarp

d) Endosperm

Option b – Bark

In onion, Food is stored in –

a) Root

b) Bud

c) Scale leaves

d) Aerial stem

Option c – Scale leaves

The chemical name for vinegar is –

a) Citric Acid

b) Malic Acid

c) Acetic Acid

d) Pyruvic Acid

Option c – Acetic Acid

BCG vaccination is used to prevent –

a) Leprosy

b) Measles

c) Diphtheria

d) Tuberculosis

Option d – Tuberculosis

Which of the following is caused by a virus?

a) Arthritis

b) Meningitis

c) Hepatitis

d) Nephritis

Option c – Hepatitis

Exobiology is the study of –

a) Life in outer space

b) Extinct Organisms

c) Life in marine environments

d) Life on other planets

Option a – Life in outer space

Which organ functions both as an endocrine and exocrine gland?

a) Pancreas

b) Testis

c) Ovary

d) Pituitary

Option d – Pituitary

The nutritive tissue in seeds of higher plants is called –

a) Hypocotyl

b) Nucellus

c) Endosperm

d) Embryo

Option c – Endosperm

Hemoglobin contains which mineral in abundance?

a) Gold

b) Silver

c) Iron

d) Copper

Option c – Iron

Phototropic growth in plants is regulated by –

a) Ethylene

b) Cytokinin

c) Auxin

d) Gibberellin

Option c – Auxin

Which organ in humans regulates water balance?

a) Liver

b) Kidneys

c) Heart

d) Lungs

Option b – Kidneys

Kidney-shaped guard cells are found in –

a) Dicot plants

b) Monocot plants

c) Both dicots and monocots

d) Algae

Option a – Dicot plants

In Pteridophyta, the gametophyte is called –

a) Pteridophyta

b) Thallus

c) Bryophyte

d) Spermatophyte

Option a – Pteridophyta

Identify the insectivorous plant –

a) Drosera

b) Rafflesia

c) Orobanche

d) Balanophora

Option a – Drosera

Which of the following animals lacks an eardrum?

a) Toads

b) Turtles

c) Snakes

d) Tuatara

Option c – Snakes

A waterborne Disease from the following is –

a) Malaria

b) Cholera

c) Diabetes

d) Smallpox

Option b – Cholera

Chromosomes are made up of DNA and –

a) Vitamins

b) Lipids

c) Carbohydrates

d) Proteins

Option d – Proteins

In bacteria, the DNA-containing region without a nuclear membrane is called –

a) Nucleus

b) Nucleosome

c) Nucleoprotein

d) Nucleoid

Option d – Nucleoid

Match the organelles with their functions –

a) Mitochondria – Respiration; Chloroplast – Photosynthesis; Ribosome – Protein synthesis; Rough ER – Protein Transport

b) Mitochondria – Respiration; Chloroplast – Photosynthesis; Ribosome – Protein Transport; Rough ER – Protein synthesis

c) Mitochondria – Respiration; Chloroplast – Protein synthesis; Ribosome – Photosynthesis; Rough ER – Protein Transport

d) Mitochondria – Photosynthesis; Chloroplast – Respiration; Ribosome – Protein synthesis; Rough ER – Protein Transport

Option a – Mitochondria – Respiration; Chloroplast – Photosynthesis; Ribosome – Protein synthesis; Rough ER – Protein Transport

Which Animal cell organelle digests foreign substances?

a) Endoplasmic reticulum

b) Lysosome

c) Golgi body

d) Mitochondria

Option b – Lysosome

Protein synthesis in a mammalian cell occurs in –

a) Ribosome

b) Golgi body

c) Lysosome

d) Smooth endoplasmic reticulum

Option a – Ribosome

The organelle not surrounded by a membrane is –

a) Lysosome

b) Ribosome

c) Nucleus

d) Golgi apparatus

Option b – Ribosome

DNA barcoding can be used to –

a) Assess age of plants/animals

b) Detect unwanted Animal or plant materials in Food

c) Both 1 and 2

d) Distinguish similar-looking species and detect unwanted materials

Option d – Distinguish similar-looking species and detect unwanted materials

The Transport of substances against a concentration gradient using energy is called ( Difficult Biology mcq for Competitive Exams )

a) Passive Transport

b) Active Transport

c) Solute loss

d) Water potential gradient

Option b – Active Transport

Movement of materials inside the cytoplasm and nucleus is facilitated by ( Difficult Biology mcq for Competitive Exams )

a) Ribosomes

b) Mitochondria

c) Lysosomes

d) Endoplasmic reticulum

Option d – Endoplasmic reticulum

ATP is synthesized in mitochondria at ( Difficult Biology mcq for Competitive Exams )

a) Outer membrane

b) Matrix

c) Inner membrane

d) Mitochondrial DNA

Option c – Inner membrane

What happens to RBCs in a 2% detergent solution? ( Difficult Biology mcq for Competitive Exams )

a) Shrink

b) Swell and become turgid

c) Swell and burst

d) Lyse

Option d – Lyse

Plant plastids that store starch, oil, and protein granules are ( Difficult Biology mcq for Competitive Exams )

a) Chloroplast

b) Leucoplast

c) Chromoplast

d) Xanthoplast

Option b – Leucoplast

Lipid synthesis occurs in which organelle? ( Difficult Biology mcq for Competitive Exams )

a) Smooth endoplasmic reticulum

b) Golgi body

c) Lysosomes

d) Mitochondria

Option a – Smooth endoplasmic reticulum

Which statement about vacuoles is incorrect? ( Difficult Biology mcq for Competitive Exams )

a) Large central vacuole in plants may occupy 90% of cell volume

b) Vacuoles give turgidity and rigidity in plant cells

c) Vacuoles help in Nutrition in Amoeba

d) Vacuoles are absent in Animal cells

Option d – Vacuoles are absent in Animal cells

Which statement correctly differentiates Animal and plant cells? ( Difficult Biology MCQ for Competitive Exams )

a) Animal cells have only a cell membrane, plant cells have only a cell wall

b) Animal cells have only a cell membrane, plant cells have both membrane and wall

c) Both Animal and plant cells have membrane and wall

d) Some animal cells have wall; all plant cells have membrane

Option a – Animal cells have only a cell membrane, plant cells have only a cell wall

Digestive enzymes in cells are present in ( Difficult Biology MCQ for Competitive Exams )

a) Mitochondria

b) Vacuoles

c) Lysosomes

d) Ribosomes

Option c – Lysosomes

When an animal cell is placed in a medium with lower water concentration, it ( Difficult Biology MCQ for Competitive Exams )

a) Loses water

b) Shows no water movement

c) Gains water

d) Swells

Option a – Loses water

The structure not found in prokaryotic cells is ( Difficult Biology MCQ for Competitive Exams )

a) Cell wall

b) Ribosomes

c) Plasma membrane

d) Nucleus

Option d – Nucleus

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