Biology MCQs

Science

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.

1922
Total Questions

Practice Questions

Page 3 of 97
Question #41
According to Mendel's law of segregation, the alleles for a trait separate during:
A. Gamete formation
B. Embryogenesis
C. Mitosis
D. Fertilization
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Mendel's first law (law of segregation) states that two alleles of a gene separate during gamete formation (meiosis) so that each gamete receives only one allele. This is due to the separation of homologous chromosomes in anaphase I of meiosis. Fertilization restores the diploid number. This law explains the 3:1 phenotypic ratio in monohybrid crosses. Mitosis maintains the allele pair.
This question belongs to: Science Biology
Question #42
A man with blood group AB marries a woman with blood group O. What are the possible blood groups of their children?
A. A, B, AB, and O
B. AB only
C. AB and O
D. A and B only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
The man's genotype is Iᴬ Iᴮ (AB) and the woman's genotype is ii (O). Gametes: man produces Iᴬ or Iᴮ, woman produces i only. Offspring: Iᴬ i (blood group A) and Iᴮ i (blood group B). Thus only A and B blood groups are possible. No AB (requires both Iᴬ and Iᴮ) or O (requires ii) children can be produced. This illustrates co-dominance and multiple alleles.
This question belongs to: Science Biology
Question #43
Which of the following nitrogenous bases is found in RNA but not in DNA?
A. Guanine
B. Adenine
C. Cytosine
D. Uracil
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
RNA contains uracil instead of thymine found in DNA. In DNA, adenine pairs with thymine; in RNA, adenine pairs with uracil. Adenine, guanine, and cytosine are common to both. Uracil is a pyrimidine base, structurally similar to thymine but lacking a methyl group. This distinction is used in genetic material identification and understanding transcription.
This question belongs to: Science Biology
Question #44
The process of copying genetic information from DNA to mRNA is called:
A. Translation
B. Replication
C. Transcription
D. Transformation
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Transcription is the synthesis of mRNA from the DNA template strand by RNA polymerase. It occurs in the nucleus (eukaryotes). Replication is DNA duplication. Translation is protein synthesis from mRNA. Transformation is the uptake of foreign DNA by bacteria. The central dogma: DNA → RNA → Protein. Transcription produces mRNA, tRNA, rRNA. The mRNA carries the codon sequence for protein assembly.
This question belongs to: Science Biology
Question #45
Charles Darwin proposed the theory of natural selection based on observations during his voyage on:
A. HMS Beagle
B. HMS Victory
C. HMS Endeavour
D. HMS Challenger
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Darwin traveled as a naturalist on the HMS Beagle (1831-1836) and made extensive observations, especially in the Galápagos Islands. His observations of finches' beak adaptations led to the concept of natural selection as the mechanism for evolution. 'On the Origin of Species' (1859) laid out his theory. HMS Challenger was an oceanographic expedition. HMS Endeavour was Captain Cook's ship.
This question belongs to: Science Biology
Question #46
Fossils are most commonly found in which type of rock?
A. Igneous rock
B. Volcanic rock
C. Sedimentary rock
D. Metamorphic rock
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Sedimentary rocks, such as limestone, shale, and sandstone, form in layers from accumulated sediments and preserve remains of organisms as fossils. Igneous rocks from volcanic activity and metamorphic rocks formed under high temperature/pressure rarely contain fossils. The fossil record provides evidence for evolution, showing gradual changes in species over geological time. Fossils include bones, shells, imprints, and amber inclusions.
This question belongs to: Science Biology
Question #47
Which of the following is a primary consumer in a food chain?
A. Grasshopper
B. Lion
C. Fungi
D. Eagle
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Primary consumers are herbivores that feed directly on producers (plants). Grasshopper feeds on grass/plants, thus a primary consumer. Lion and eagle are secondary/tertiary consumers (carnivores). Fungi are decomposers. In a food chain: Grass (producer) → Grasshopper (primary consumer) → Frog (secondary consumer) → Snake (tertiary consumer) → Eagle (quaternary consumer). Energy flows unidirectionally.
This question belongs to: Science Biology
Question #48
Which of the following is an example of a biodegradable pollutant?
A. Sewage
B. Mercury
C. DDT
D. Plastic
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Sewage contains organic matter that can be broken down by microorganisms, hence biodegradable. DDT, plastics, and mercury are non-biodegradable, persisting in the environment and accumulating in food chains (biomagnification). Biodegradable pollutants can be decomposed naturally, reducing long-term harm, but excessive loads can cause eutrophication. Non-biodegradable pollutants require special disposal and cause lasting ecological damage.
This question belongs to: Science Biology
Question #49
The symbiotic relationship between fungi and algae in lichens is an example of:
A. Predation
B. Commensalism
C. Parasitism
D. Mutualism
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Lichens represent mutualism where the fungal partner provides shelter, water, and minerals, and the algal or cyanobacterial partner provides food through photosynthesis. Both benefit. Parasitism is harmful to host; commensalism benefits one without affecting the other; predation involves one killing and eating the other. Lichens are bioindicators of air pollution, sensitive to SO₂. This association is obligate.
This question belongs to: Science Biology
Question #50
Which of the following microorganisms is used in the production of bread?
A. Saccharomyces cerevisiae
B. Aspergillus niger
C. Lactobacillus
D. Streptococcus
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Saccharomyces cerevisiae, commonly called baker's yeast, ferments sugars to produce CO₂ and ethanol. The CO₂ causes dough to rise, giving bread its porous texture. Lactobacillus is used in yogurt and cheese making, Aspergillus niger in citric acid production, Streptococcus in some dairy ferments. Yeast is a unicellular fungus. Fermentation is an anaerobic process. Alcohol evaporates during baking.
This question belongs to: Science Biology
Question #51
The process of growing plants in a sterile nutrient medium under controlled conditions is called:
A. Genetic engineering
B. Cloning
C. Tissue culture
D. Hybridization
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Tissue culture is a technique where plant cells, tissues, or organs are grown on a synthetic nutrient medium (like MS medium) under aseptic conditions to regenerate whole plants. It exploits totipotency. It is used for micropropagation, production of disease-free plants, and conservation. Cloning produces genetically identical individuals, genetic engineering alters DNA, hybridization crosses different varieties.
This question belongs to: Science Biology
Question #52
Which of the following is a biofertilizer commonly used for rice cultivation?
A. Azotobacter
B. Mycorrhiza
C. Rhizobium
D. Azolla
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Azolla is an aquatic fern that harbors the nitrogen-fixing cyanobacterium Anabaena azollae in its leaf cavities. It is extensively used as a biofertilizer in rice paddies, adding organic nitrogen. Rhizobium fixes nitrogen in legume roots, Azotobacter is free-living in soil, mycorrhiza is a fungal association enhancing phosphorus uptake. Azolla multiplies rapidly and improves soil fertility.
This question belongs to: Science Biology
Question #53
Apiculture is the rearing of:
A. Silkworms
B. Poultry birds
C. Honeybees
D. Fish
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Apiculture involves the maintenance of honeybee colonies for honey, beeswax, and pollination services. Sericulture is silkworm rearing, pisciculture is fish farming, poultry is bird rearing for eggs/meat. The most common species in India is Apis indica (Indian bee) and Apis mellifera (European bee). Apiculture requires knowledge of bee biology, management of hives, and disease control.
This question belongs to: Science Biology
Question #54
Alexander Fleming discovered the antibiotic penicillin from the fungus:
A. Agaricus bisporus
B. Penicillium chrysogenum
C. Aspergillus fumigatus
D. Saccharomyces cerevisiae
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Fleming accidentally discovered penicillin in 1928 when a mold contaminant (later identified as Penicillium notatum/now Penicillium chrysogenum) inhibited bacterial growth. This led to the first widely used antibiotic. Aspergillus species produce some toxins and acids, Saccharomyces is yeast, Agaricus bisporus is the common mushroom. Penicillin acts by disrupting bacterial cell wall synthesis.
This question belongs to: Science Biology
Question #55
Which scientist first observed and described living cells?
A. Robert Hooke
B. Matthias Schleiden
C. Rudolf Virchow
D. Antonie van Leeuwenhoek
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Antonie van Leeuwenhoek, a Dutch microscopist, designed single-lens microscopes and observed bacteria, protozoa, sperm cells, and RBCs for the first time, calling them 'animalcules'. Hooke observed dead cork cells. Schleiden proposed that plants are composed of cells, Virchow stated 'Omnis cellula e cellula'. Leeuwenhoek is rightly considered the father of microbiology for his pioneering observations of living microbes.
This question belongs to: Science Biology
Question #56
Which of the following is a difference between plant and animal cells?
A. Plant cells have centrioles; animal cells lack centrioles.
B. Animal cells have vacuoles; plant cells lack vacuoles.
C. Plant cells have a plasma membrane; animal cells do not.
D. Plant cells have a cell wall and chloroplasts; animal cells lack these.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Plant cells possess a rigid cell wall of cellulose, chloroplasts for photosynthesis, and a large central vacuole. Animal cells lack cell wall and chloroplasts, and have small temporary vacuoles if present. Centrioles are present in animal cells (centrosome) but absent in higher plant cells. Both have plasma membrane. The cell wall provides shape and protection. These differences are fundamental in cell biology.
This question belongs to: Science Biology
Question #57
Lysosomes are rich in which type of enzymes?
A. Isomerases
B. Transferases
C. Hydrolytic enzymes
D. Oxidoreductases
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Lysosomes contain about 40 types of hydrolytic enzymes (hydrolases) like proteases, lipases, nucleases, glycosidases, which digest macromolecules. They function in acidic pH (5.0). Oxidoreductases catalyze oxidation-reduction, transferases transfer groups, isomerases catalyze isomerization. Lysosomes are involved in autophagy, phagocytosis, and programmed cell death. Their rupture leads to autolysis, hence called 'suicide bags'.
This question belongs to: Science Biology
Question #58
In meiosis, the reduction in chromosome number occurs in which division?
A. Only during interphase before meiosis I
B. Meiosis I
C. Meiosis II
D. Both meiosis I and II equally
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Meiosis I is the reductional division where homologous chromosomes separate, reducing the chromosome number from diploid (2n) to haploid (n). Meiosis II is equational division, similar to mitosis, separating sister chromatids. Thus, reduction occurs in anaphase I. DNA replication occurs in S phase before meiosis I. Gametes are haploid. Errors in reduction can lead to aneuploidy.
This question belongs to: Science Biology
Question #59
Which of the following is NOT a part of the endomembrane system?
A. Lysosomes
B. Endoplasmic reticulum
C. Golgi apparatus
D. Mitochondria
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
The endomembrane system includes ER, Golgi apparatus, lysosomes, vacuoles, and the nuclear envelope—organelles that coordinate membrane flow and protein processing. Mitochondria (and chloroplasts) are not part of this system because they are semi-autonomous, arising from endosymbiosis, and are not connected by vesicle trafficking. Peroxisomes are sometimes considered associated but not part of the ER-derived system.
This question belongs to: Science Biology
Question #60
In the five-kingdom classification, the kingdom Protista includes:
A. Mushrooms and molds
B. Multicellular algae and bryophytes
C. Bacteria and cyanobacteria
D. Unicellular eukaryotes like amoeba and paramecium
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Protista includes unicellular eukaryotes such as protozoans (Amoeba, Paramecium), unicellular algae (Chlamydomonas, diatoms), and slime molds. They may be autotrophic or heterotrophic. Monera contains prokaryotes. Fungi include multicellular (except yeast) saprophytes. Plantae includes multicellular autotrophs. The protist kingdom is a 'catch-all' group for eukaryotes not fitting into fungi, plantae, or animalia.
This question belongs to: Science Biology

More Science Topics

chemistry MCQs
Physics MCQs
Today's Top Topics
Biology 1922 Physics 1287 chemistry 1089
Explore Subjects
Computer 5279 Maths 5575 Accountancy and Statistics 3179 Science 4298 Static General Knowledge 6362
Practice Mix
Which of the following describes a precompiled collection of SQL statements stored on the database server that can be executed repeatedly by name?
Which major corporate computing entity was founded directly from the evolution of Herman Hollerith’s Tabulating Machine Company?
Total Fertility Rate (TFR) of 2.5 indicates that, on average, women are having:
Choose the antonym of 'YEARNING'.
The median of the dataset: 10, 15, 20, 25, 30, 35 is: