All Free Biology MCQs with Answers

931. Haemophilia is

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

Explanation: Haemophilia is an X-linked recessive disorder affecting blood clotting, more common in males.

932. Linkage between genes

• A. Increases with distance on chromosome
• B. Decreases with distance
• C. Is unaffected by distance
• D. Only occurs on sex chromosomes

Explanation: Linkage decreases with distance; genes farther apart cross over more frequently. 1% recombination = 1 map unit.

933. In Hardy-Weinberg equilibrium, p² represents

• A. Heterozygote frequency
• B. Homozygous dominant frequency
• C. Homozygous recessive frequency
• D. Total alleles

Explanation: p² = frequency of homozygous dominant (AA), 2pq = heterozygous (Aa), q² = homozygous recessive (aa).

934. Polygenic inheritance involves

• A. One gene with two alleles
• B. Multiple genes affecting one trait
• C. Genes on sex chromosomes only
• D. Mitochondrial genes

Explanation: Polygenic traits (height, skin color) are controlled by multiple genes, showing continuous variation.

935. A carrier of an X-linked recessive disorder is

• A. Male with the disorder
• B. Female with one affected X
• C. Female with both X affected
• D. Male without the disorder

Explanation: Carrier females are heterozygous (XAXa) and phenotypically normal but can pass the allele to offspring.

936. Pleiotropy refers to

• A. One gene affecting multiple traits
• B. Multiple genes affecting one trait
• C. Genes on same chromosome
• D. Genes affecting only one tissue

Explanation: Pleiotropy is when one gene affects multiple phenotypic traits, e.g., sickle cell gene affects multiple organs.

937. Spermatogenesis occurs in the

• A. Epididymis
• B. Seminiferous tubules
• C. Vas deferens
• D. Seminal vesicle

Explanation: Spermatogenesis (sperm production) occurs in the seminiferous tubules of the testes.

938. The acrosome contains

• A. Mitochondria
• B. Digestive enzymes
• C. DNA
• D. Flagellar proteins

Explanation: The acrosome contains hydrolytic enzymes (hyaluronidase, proteases) that help sperm penetrate the egg.

939. Ovulation is triggered by

• A. FSH surge
• B. LH surge
• C. Estrogen decrease
• D. Progesterone increase

Explanation: The LH surge (luteinizing hormone) triggers ovulation, releasing the mature egg from the Graafian follicle.

940. The corpus luteum secretes

• A. FSH and LH
• B. Estrogen and progesterone
• C. hCG
• D. Prolactin

Explanation: The corpus luteum (formed from the ruptured follicle) secretes progesterone and estrogen to maintain the endometrium.