Biology MCQs

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Biology MCQs

Practice complete Biology MCQs covering Introduction to Biology, Cell Biology, Cell Structure, Cell Division, Biomolecules, Plant Physiology, Human Physiology, Genetics, Evolution, Biotechnology, Ecology, Classification of Living Organisms, Plant Kingdom, Animal Kingdom, Microbiology, Human Diseases, Nutrition, Reproduction, Environmental Biology, and all other important topics. Includes chapter-wise and exam-oriented multiple-choice questions with detailed answers and explanations for JKSSB, SSC, Banking, Railway, UPSC, CUET, NEET, State PSCs, and other competitive exams.

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Page 102 of 103
Question #2021
The bacteria used in the production of curd from milk is:
A. Lactobacillus
B. Salmonella
C. Bacillus
D. Vibrio
Discuss
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Correct Answer: Option A

Explanation:
Lactobacillus species convert lactose to lactic acid, lowering pH and coagulating milk proteins to form curd. It is a probiotic.
This question belongs to: Science Biology
Question #2022
Which microorganism is used in baking industry for bread?
A. Algae
B. Yeast (Saccharomyces)
C. Bacteria
D. Virus
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Correct Answer: Option B

Explanation:
Saccharomyces cerevisiae (baker's yeast) ferments sugars, producing COâ‚‚ that leavens dough. Alcohol evaporates during baking.
This question belongs to: Science Biology
Question #2023
The antibiotic penicillin is obtained from:
A. Protozoa
B. Bacteria
C. Algae
D. Fungus
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Correct Answer: Option D

Explanation:
Penicillin is derived from the fungus Penicillium chrysogenum (formerly P. notatum). Alexander Fleming discovered it in 1928.
This question belongs to: Science Biology
Question #2024
The technique of growing plants under controlled conditions in a sterile medium is:
A. Genetic engineering
B. Hydroponics
C. Cloning
D. Tissue culture
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Correct Answer: Option D

Explanation:
Tissue culture involves growing plant cells, tissues, or organs on a nutrient medium under aseptic conditions to produce clones or disease-free plants.
This question belongs to: Science Biology
Question #2025
Bt cotton is genetically modified to resist:
A. Salinity
B. Bollworm pests
C. Drought
D. Herbicides
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Correct Answer: Option B

Explanation:
Bt cotton contains cry genes from Bacillus thuringiensis, producing insecticidal proteins toxic to bollworms, reducing pesticide use.
This question belongs to: Science Biology
Question #2026
The process of copying DNA to produce identical DNA is:
A. Mutation
B. Replication
C. Transcription
D. Translation
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Correct Answer: Option B

Explanation:
DNA replication is semiconservative, producing two identical copies from a template. Transcription makes RNA, translation makes protein.
This question belongs to: Science Biology
Question #2027
PCR is a technique used to:
A. Separate DNA fragments
B. Amplify a specific DNA sequence
C. Sequence DNA
D. Cut DNA
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Correct Answer: Option B

Explanation:
Polymerase chain reaction (PCR) uses Taq polymerase and primers to exponentially amplify a target DNA segment in vitro.
This question belongs to: Science Biology
Question #2028
The first cloned mammal, Dolly the sheep, was created using:
A. Artificial insemination
B. In vitro fertilization
C. Recombinant DNA
D. Somatic cell nuclear transfer
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Correct Answer: Option D

Explanation:
Dolly was cloned by transferring the nucleus from an adult somatic (mammary) cell into an enucleated egg, then implanted in a surrogate.
This question belongs to: Science Biology
Question #2029
Which of the following is a transgenic crop?
A. Golden rice
B. Sugarcane
C. Basmati rice
D. Traditional wheat
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Correct Answer: Option A

Explanation:
Golden rice is genetically engineered to produce beta-carotene (provitamin A) in the endosperm, to address vitamin A deficiency.
This question belongs to: Science Biology
Question #2030
The enzyme that cuts DNA at specific sequences is:
A. Restriction endonuclease
B. Helicase
C. Ligase
D. Polymerase
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Correct Answer: Option A

Explanation:
Restriction enzymes recognize specific palindromic sequences and cleave the DNA backbone, producing sticky or blunt ends for cloning.
This question belongs to: Science Biology
Question #2031
Which scientist discovered the process of pasteurization?
A. Robert Koch
B. Alexander Fleming
C. Louis Pasteur
D. Edward Jenner
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Correct Answer: Option C

Explanation:
Louis Pasteur developed pasteurization (heating to kill spoilage organisms), vaccines for rabies and anthrax, and disproved spontaneous generation.
This question belongs to: Science Biology
Question #2032
The scientist who proved that microorganisms cause disease was:
A. Robert Koch
B. Antonie van Leeuwenhoek
C. Joseph Lister
D. Louis Pasteur
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Correct Answer: Option A

Explanation:
Robert Koch established Koch's postulates, demonstrating that specific microbes cause specific diseases (anthrax, tuberculosis, cholera).
This question belongs to: Science Biology
Question #2033
Who is known as the father of genetics?
A. Hugo de Vries
B. Charles Darwin
C. Thomas Morgan
D. Gregor Mendel
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Correct Answer: Option D

Explanation:
Gregor Mendel's experiments on pea plants led to the discovery of the fundamental laws of inheritance, earning him the title father of genetics.
This question belongs to: Science Biology
Question #2034
The double helix model of DNA was given by:
A. Hershey and Chase
B. Beadle and Tatum
C. Watson and Crick
D. Mendel and Morgan
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Correct Answer: Option C

Explanation:
James Watson and Francis Crick, using Rosalind Franklin's X-ray data, proposed the double helical structure of DNA in 1953.
This question belongs to: Science Biology
Question #2035
The hormone that stimulates the thyroid gland to secrete thyroxine is:
A. FSH
B. TSH
C. LH
D. ACTH
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Correct Answer: Option B

Explanation:
Thyroid-stimulating hormone (TSH) from the anterior pituitary binds to thyroid follicular cells, stimulating the release of T₃ and T₄.
This question belongs to: Science Biology
Question #2036
Which of the following is a function of the liver?
A. Filtration of urine
B. Production of thyroxine
C. Production of bile
D. Production of insulin
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Correct Answer: Option C

Explanation:
The liver produces bile, metabolizes nutrients, detoxifies, stores glycogen, and synthesizes plasma proteins. Insulin is from pancreas.
This question belongs to: Science Biology
Question #2037
The functional unit of the human lung is:
A. Neuron
B. Nephron
C. Alveolus
D. Villus
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Correct Answer: Option C

Explanation:
Alveoli are tiny air sacs where gas exchange occurs between air and blood. Nephrons are kidney units, neurons nerve cells.
This question belongs to: Science Biology
Question #2038
Which part of the brain controls breathing and heart rate?
A. Cerebrum
B. Medulla oblongata
C. Hypothalamus
D. Cerebellum
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Correct Answer: Option B

Explanation:
The medulla oblongata contains vital reflex centers for respiration, cardiovascular function, and digestion. It is part of the brainstem.
This question belongs to: Science Biology
Question #2039
The largest gland in the human body is:
A. Liver
B. Pancreas
C. Pituitary
D. Thyroid
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Correct Answer: Option A

Explanation:
The liver is the largest internal organ and gland, weighing about 1.5 kg. It performs metabolic, detoxification, and synthetic functions.
This question belongs to: Science Biology
Question #2040
The disease caused by iodine deficiency is:
A. Rickets
B. Beri-beri
C. Anemia
D. Goiter
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Correct Answer: Option D

Explanation:
Iodine deficiency impairs thyroid hormone synthesis, leading to elevated TSH and enlargement of the thyroid gland (goiter). Iodized salt prevents it.
This question belongs to: Science Biology

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