All Free Biology MCQs with Answers

• A. Growth hormone
• B. Follicle stimulating hormone
• C. Oxytocin
• D. Adrenocorticotropic hormone

Explanation: Oxytocin is not a hormone of the anterior pituitary. It is produced by the hypothalamus and released from the posterior pituitary gland.

• A. Pituitary gland
• B. Thyroid gland
• C. Parathyroid gland
• D. Adrenal gland

Explanation: Oxytocin is secreted by the pituitary gland. Specifically, it is produced by the hypothalamus and released from the posterior pituitary…

• A. Testosterone
• B. Progesterone
• C. Estrogen
• D. Thyroxin

Explanation: Estrogen is the hormone responsible for causing the mammary glands to enlarge at puberty.

• A. Adrenal
• B. Anterior pituitary
• C. Posterior pituitary
• D. Thyroid

Explanation: The anterior pituitary gland secretes the gonadotropic hormones, which include follicle-stimulating hormone (FSH) and luteinizing hormone…

• A. Estrogen
• B. FSH
• C. Prolactin
• D. Oxytocin

Explanation: The most important hormone in initiating and maintaining lactation after birth is prolactin.

• A. Mesosome
• B. polysome
• C. Nucleosome
• D. Centrosome

Explanation: Mesosomes are a convoluted membranous structure formed in a prokaryotic cell by the invagination of the plasma membrane.

• A. Prophase
• B. Metaphase
• C. Anaphase
• D. Telophase

Explanation: The correct answer is Prophase. This stage initiates the condensation of chromosomes, reaching their maximum compaction.

• A. Histone
• B. RNA
• C. DNA
• D. All of the above

Explanation: The material controlling heredity in chromosomes is DNA. DNA carries genetic information and directly influences hereditary traits in…

• A. Down's syndrome
• B. Turner's syndrome
• C. Jacobs syndrome
• D. Klinefilter's syndrome

Explanation: Klinefelter's syndrome is characterized by the presence of an additional X chromosome in males.

• A. Prophase
• B. Metaphase
• C. Anaphase
• D. Telophase

Explanation: During the process of cell division, specifically in mitosis or meiosis, condensation of chromosomes occurs.

• A. two daughter cells
• B. sister chromatids
• C. mitosis
• D. unregulated growth

Explanation: Cell division Mitosis or meiosis results in the formation of daughter cells from the division of the parent cell.

• A. 43
• B. 1.29
• C. 0.43
• D. 24

Explanation: The total number of chromosomes present in a tobacco plant is 24, therefore option 'D' is correct.

• A. 1 nm
• B. 2 nm
• C. 3 nm
• D. 4 nm

Explanation: A histone is a protein that provides structural support to a chromosome.

• A. 45
• B. 48
• C. 46
• D. 47

Explanation: The correct number of chromosomes in tobacco is 48. Tobacco is an allopolyploid species, which means it has multiple sets of chromosomes…

• A. Genotype
• B. Phenotype
• C. Karyotype
• D. Genome

Explanation: The correct answer is Karyotype. A karyotype is a visual profile of an individual's chromosomes, showing the number and appearance of…

• A. Number
• B. Inheritance
• C. Heredity
• D. Composition

Explanation: Genes are specific sequences of nucleotides within DNA that reside on chromosomes.

• A. XXY
• B. XY
• C. XYY
• D. XYYY

Explanation: In Down's syndrome, the affected person contains an extra autosomal chromosome number 21 (trisomy 2n+1).

• A. Tadpole Larvae
• B. Frog
• C. Trochophere larvae
• D. Salamander larvae

Explanation: When scientists first observed chromosomes in the dividing cells of salamander larvae, they noticed these thread-like structures that…

• A. Translocation
• B. Linkage
• C. Mutation
• D. Nondisjunction

Explanation: A permanent change in the genetic structure of a gene is called a mutation.

• A. Metacentric
• B. Sub metacentric
• C. Acrocentric
• D. Telocentric

Explanation: An acrocentric chromosome is a chromosome in which the centromere is located very close to one end, creating a long arm (q) and a short…