All Free Biology MCQs with Answers

• A. Dietary rickets
• B. Hypophosphatemic rickets
• C. Osteomalacia
• D. General bone weakness

Explanation: The correct answer is Hypophosphatemic rickets. This condition is not resolved by vitamin D supplementation because it stems from a…

• A. X-linked recessive traits
• B. Y-linked traits
• C. X-linked dominant traits
• D. X-linked traits

Explanation: The correct answer is Y-linked traits. This is because Y-linked traits are located on the Y chromosome, which only males possess.

• A. A: 3/16
• B. B: 1/16
• C. C: 9/16
• D. D: 6/16

Explanation: The expected phenotypic ratio in the F2 generation of a dihybrid cross (AaBb x AaBb) is 9:3:3:1, indicating that there are three different…

• A. Sixteen years after his death
• B. Twenty years after his death
• C. Twenty-four years after his death
• D. Thirty-four years after his death

Explanation: In 1900, 16 years after Mendel's death, three botanists-Carl Correns, Hugo de Vries, and Erich von Tschermak-independently rediscovered…

• A. Mouse and Rabbit
• B. Dog and Sheep
• C. Donkey and Horse
• D. Mouse, rabbit, dog, sheep, donkey, cattle, kangaroo, and chimpanzee

Explanation: The correct answer is the option that lists mouse, rabbit, dog, sheep, donkey, cattle, kangaroo, and chimpanzee.

• A. Pleiotropy
• B. Epistasis
• C. Overdominance
• D. Co-dominance

Explanation: The correct answer is epistasis. Epistasis is a genetic phenomenon where the effect of one gene (the epistatic gene) interferes with or…

• A. Different alleles of the same gene
• B. Different genes occupying different loci
• C. Same gene of different loci
• D. Different genes occupying the same locus

Explanation: Epistasis is an interaction between different genes at different loci, where one gene (epistatic) can modify or mask the expression of…

• A. IAIB
• B. IBi
• C. IAIA or IAi
• D. ii

Explanation: The genotype IAIA is homozygous for allele IA, which produces phenotype A.

• A. Puberty
• B. Old age
• C. Death
• D. Eighties

Explanation: The blood group alleles start expressing themselves during the early embryonic stage and continue to express throughout an individual's…

• A. Does not cause agglutination in the recipient
• B. Causes agglutination in the recipient
• C. Does not cause agglutination in the donor
• D. Causes agglutination in the donor

Explanation: The correct answer is that a safe blood transfusion does not cause agglutination in the recipient.

• A. The recipient's RBCs are destroyed
• B. Either recipient's or donor's RBCs or both are destroyed
• C. The donor's RBCs are destroyed
• D. No RBCs are destroyed

Explanation: Incompatible blood transfusions occur when the blood type of the donor and recipient do not match properly, leading to an immune response.

• A. 23 autosomes, one pair of sex chromosomes
• B. 22 autosomes, one pair of sex chromosomes
• C. 23 pairs of autosomes, one pair of sex chromosomes
• D. 22 pairs of autosomes, one pair of sex chromosomes

Explanation: Humans have a total of 46 chromosomes, organized into 23 pairs. Out of these, 22 pairs are known as autosomes, and they are the same in…

• A. Same type of gametes are produced
• B. Same type of sperms are produced
• C. Same type of eggs are produced
• D. Different type of eggs are produced

Explanation: In humans, gamete production differs between males and females. Males produce two types of sperm - one carrying the X chromosome and the…

• A. Allelomorphs
• B. Fixed alleles
• C. Multiple alleles
• D. Pseudoalleles

Explanation: The correct answer is Multiple alleles. This term describes a scenario where a gene has more than two variants or forms in a population.

• A. Charles Darwin
• B. Nilsson-Ehle
• C. Gregor Mendel
• D. Carl Correns

Explanation: Nilsson-Ehle studied the genetics of wheat grain color and demonstrated that it is a polygenic trait.

• A. Two to three gene pairs
• B. Three to four gene pairs
• C. Four to five gene pairs
• D. Three to six gene pairs

Explanation: Human skin color is a quantitative trait influenced by three to six gene pairs.

• A. Alleles of two or more different gene pairs
• B. Alleles of a single gene pair
• C. Alleles of two or more genomes
• D. Multiple alleles of a single gene

Explanation: A continuously varying trait, also known as a quantitative trait, is typically influenced by alleles of two or more different gene pairs…

• A. Taxonomy
• B. Ecology
• C. Morphology
• D. Physiology

Explanation: Taxonomy is the branch of biology that deals with the classification, naming, and identification of organisms.

• A. They provide a beautiful area for recreation
• B. One can observe tropical plants there
• C. They allow ex-situ conservation of germplasm
• D. They provide a natural habitat for wildlife

Explanation: Ex-situ conservation means "off-site conservation." It is the process of protecting endangered species of plants and animals by removing…

• A. Fibrous Joints
• B. Cartilaginous Joints
• C. Synovial Joints
• D. None of these

Explanation: Option A is correct since fibrous joints are connected by dense, tough connective tissue that is rich in collagen fibers.