Biology Test 122

The epiglottis moves back and forth to prevent the passage of food and liquids into the lungs. The usual upright position of the epiglottis allows air to flow into the lungs and the larynx. When you swallow, the epiglottis flattens backward to cover the entrance to your larynx and prevent food from entering the lungs and windpipe. The epiglottis returns to its usual position after swallowing. 

Hence, the correct option is (B).

The guinea pig, different from other laboratory rodents, has a rather long gestation period (up to 70 days), it is handy, patient and easily bred; it has an endocrine pregnancy control similar to that of the human, and it has a discoidal, hemomonochorial placenta with a fetal/maternal transport barrier which is very similar to that of the human placenta.

Hence, the correct option is (C).

Bacteriology, a branch of microbiology dealing with the study of bacteria. It comprises the identification, classification and characterization of bacterial species.

Hence, the correct option is (A).

Useful genes are incorporated into a variety through genetic engineering methods of crop improvement by means of plasmids, co-cultivation and microinjection.

A plasmid is a small DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. Artificial plasmids are widely used as vectors in molecular cloning, serving to drive the replication of recombinant DNA sequences within host organisms.

Microinjection is the use of a glass micropipette to inject a liquid substance at a microscopic or borderline macroscopic level. 

Co-cultivation refers to the simultaneous cultivation of two or more species of microorganism, or types of tissue, in the same medium, thereby incorporating useful genes in the desired crop.

Hence, the correct option is (D).

Sweet potatoes (Ipomoea batatas) are modified adventitious roots. They are swollen and contain a high amount of starch. Other examples of modified adventitious roots include cassava, dahlia.

Hence, the correct option is (A).

Females have two X chromosomes in their cells, while males have both X and Y chromosomes in their cells. Egg cells all contain an X chromosome, while sperm cells contain an X or Y chromosome. This arrangement means that it is the male that determines the sex of the offspring when fertilization occurs.

Hence, the correct option is (A).

Phytochrome is a photoreceptor, a pigment that plants use to detect light. It is sensitive to light in the red and far-red regions of the visible spectrum. Many flowering plants use it to regulate the time of flowering based on the length of day and night (photoperiodism) and to set circadian rhythms. P_fr promotes the germination of seeds.

Hence, the correct option is (A).

The pituitary releases LH when the level of blood testosterone falls, which has positive feedback with the hypothalamus and the anterior pituitary gland.
Hence, the correct option is (D).

Hydrilla is used in test tube funnel experiment. The test tube funnel experiment demonstrates that oxygen is evolved during photosynthesis. A few branches of Hydrilla are kept in a beaker containing pond water in which a small amount of sodium bicarbonate is dissolved.

Hence, the correct option is (D).

Ecosystem diversity deals with the variations in ecosystems within a geographical location and their overall impact on human existence and the environment. Ecological diversity is a type of biodiversity. It is the variation in the ecosystems found in a region or the variation in ecosystems over the whole planet.

Hence, the correct option is (D).