Question 1

In wind-pollinated (anemophilous) plants such as maize and grasses, flowers are typically characterized by:

Accepted Answer

Feathery stigmas and light, non-sticky pollen grains. Anemophilous flowers have feathery/plumose stigmas, light dry pollen, and often lack petals and nectar.

Question 2

The viability of pollen grains in cereals such as wheat and rice after being shed from the anther is approximately:

Accepted Answer

30 minutes. Cereal pollen is short-lived (~30 minutes) due to rapid desiccation; some species (legumes) last longer.

Question 3

In human males, the physiological failure of the testes to descend from the abdominal cavity into the scrotum during fetal life is termed:

Accepted Answer

Cryptorchidism. Cryptorchidism: undescended testis — causes infertility due to higher abdominal temperature inhibiting spermatogenesis.

Question 4

The dense, fibrous white connective tissue capsule that immediately covers the testis proper beneath the tunica vaginalis is the:

Accepted Answer

Tunica albuginea. Tunica albuginea is the tough fibrous capsule encasing the testis, giving it structural support.

Question 5

Which phase of the human menstrual cycle is also referred to as the secretory or luteal phase?

Accepted Answer

Days 15 to 28. The secretory/luteal phase (days 15–28) is dominated by progesterone from the corpus luteum.

Question 6

A condensation of inactivated chromatin observed as a dark-staining heteropycnotic body at the periphery of the nucleus in female somatic cells is called a:

Accepted Answer

Barr body. Barr body: inactivated X chromosome condensed at the nuclear periphery in female (XX) cells.

Question 7

In 1944, Avery, MacLeod, and McCarty demonstrated that the transforming principle in 	extit{Streptococcus pneumoniae} was destroyed ONLY when treated with:

Accepted Answer

Deoxyribonuclease (DNase). DNase destroyed the transforming principle, proving DNA (not protein or RNA) was the genetic material.

Question 8

The enzyme responsible for continuous elongation of both leading and lagging DNA strands in 	extit{E. coli} is:

Accepted Answer

DNA polymerase III holoenzyme. DNA Pol III is the principal replicative enzyme in E. coli, synthesizing both leading and lagging strands.

Question 9

A single base pair substitution that converts an amino acid codon into a premature stop codon (e.g., UAA, UAG, or UGA) is called a:

Accepted Answer

Nonsense mutation. Nonsense mutation: base substitution creates a premature stop codon, truncating the protein.

Question 10

The evolutionary process wherein two distinct species with different ancestries independently develop similar functional structures in response to similar environments is:

Accepted Answer

Convergent evolution. Convergent evolution produces analogous structures in unrelated taxa facing similar selection pressures.

Question 11

The positive hydrostatic pressure that develops in xylem tracheary elements due to active metabolic absorption of water by root cells is measured by a:

Accepted Answer

Manometer. A manometer measures root pressure (positive hydrostatic pressure in xylem due to active root absorption).

Question 12

The shift of the oxygen-hemoglobin dissociation curve to the right due to an increase in blood PCO_2 or a decrease in pH is designated as the:

Accepted Answer

Bohr effect. Bohr effect: increased CO₂/H⁺ reduces Hb-O₂ affinity (rightward shift), promoting O₂ unloading in tissues.

Question 13

The high-velocity conduction of nerve impulses jumping from one node of Ranvier to the next along a myelinated axon is called:

Accepted Answer

Saltatory conduction. Saltatory conduction: action potentials jump between nodes of Ranvier, greatly increasing conduction speed.

Question 14

The primary recombinant DNA vaccine developed and produced commercially using transgenic yeast cells (	extit{Saccharomyces cerevisiae}) protects against:

Accepted Answer

Hepatitis B. Hepatitis B vaccine (HBsAg) was the first recombinant vaccine, produced in yeast.

Question 15

In angiosperms, the entry of the pollen tube through the integuments of an ovule is termed:

Accepted Answer

Mesogamy. Mesogamy: pollen tube enters through the integuments (not via micropyle or chalaza).

Question 16

The non-cellular, homogeneous glycoprotein coat that immediately envelopes the secondary oocyte during ovulation is the:

Accepted Answer

Zona pellucida. Zona pellucida is the glycoprotein matrix surrounding the oocyte, mediating sperm binding and acrosome reaction.

Question 17

Mendel formulated the Law of Segregation (Purity of Gametes) based directly on his observations from:

Accepted Answer

Monohybrid crosses. The Law of Segregation was derived from monohybrid cross results (3:1 ratio in F₂).

Question 18

The core promoter DNA sequence recognized by the transcription apparatus in eukaryotic genes, situated approximately 25-30 base pairs upstream of the transcription start site, is the:

Accepted Answer

TATA box (Goldberg-Hogness box). TATA box (~25–30 bp upstream) is bound by TBP (TATA-binding protein) to position RNA Pol II.

Question 19

The geological era commonly known as the "Age of Reptiles", spanning the Triassic, Jurassic, and Cretaceous periods, is the:

Accepted Answer

Mesozoic era. Mesozoic era (252–66 Mya): dominated by reptiles including dinosaurs.

Question 20

The primary acceptor of carbon dioxide in the mesophyll chloroplasts of C_4 plants is:

Accepted Answer

Phosphoenolpyruvate (PEP). PEP carboxylase in mesophyll cells fixes CO₂ onto PEP to form OAA (4-carbon acid).

Biology - 4 — MH-CET Full Length Paper MCQs with Solutions

Sample questions with solutions