OAT Biology Practice Test

Question 1

All of these play an important role in human respiration EXCEPT

Accepted Answer

A decrease in the amount of O2 in the blood

Answer

Human respiration is primarily regulated by chemoreceptors that are highly sensitive to changes in blood CO2 levels and pH (which is affected by CO2). An increase in CO2 or a decrease in pH strongly stimulates breathing to expel CO2. While a decrease in blood O2 (hypoxemia) does stimulate respiration, it is a less potent and less sensitive stimulus compared to CO2/pH, only becoming significant when O2 levels drop substantially. Therefore, a decrease in O2 plays a less important role in the *normal* regulation of respiration compared to the other factors listed.

Question 2

Animal cells vary from plant cells in that they have

Accepted Answer

Centrioles within centrosomes

Answer

Animal cells differ from plant cells in several key ways. Animal cells possess centrioles, which are involved in cell division and the formation of cilia and flagella, located within centrosomes. Higher plant cells, in contrast, typically lack centrioles. Plant cells have a rigid cell wall made of cellulose and a large central vacuole, which are absent in animal cells, while lysosomes are more prominent in animal cells, though plant vacuoles can perform similar functions.

Question 3

The liver is an important organ that performs all of the functions listed below. EXCEPT

Accepted Answer

Breaking down peptides into amino acids

Answer

The liver performs numerous vital functions, including detoxification of harmful substances, storage of glycogen, and extensive metabolism of amino acids. However, the primary site for breaking down peptides into individual amino acids is the gastrointestinal tract, specifically in the stomach by pepsin and in the small intestine by pancreatic proteases (like trypsin and chymotrypsin) and brush border peptidases. The liver receives amino acids from the small intestine but does not perform the initial peptide breakdown.

Question 4

A symbiotic relationship is defined as which of the following?

Accepted Answer

Remora fish eat parasites off of sharks; the sharks stay free of parasites, and the remora fish are protected from predators

Answer

A symbiotic relationship describes a close and long-term interaction between two different biological organisms. Option D, where remora fish eat parasites off sharks (benefiting the shark) and are protected from predators (benefiting the remora), is an example of mutualism. Mutualism is a type of symbiosis where both species benefit from the interaction, making it a clear and illustrative example of a symbiotic relationship.

Question 5

Calypso bulbosa, the Calypso Orchid, grows in close proximity to mycorrhizal fungi. The fungus infiltrate the flower's 
roots and take use of the plant's food supply. Rare minerals, such as phosphates, are concentrated in the roots by the 
fungi and made readily available to the orchid. This is an example of

Accepted Answer

Mutualism

Answer

The relationship between the Calypso Orchid and mycorrhizal fungi is an example of mutualism. The fungi benefit by obtaining food (carbohydrates) from the plant, while the orchid benefits from the fungi's ability to concentrate and make rare minerals, such as phosphates, readily available to its roots. Since both organisms derive a clear benefit from this close interaction, it is classified as mutualism.

OAT - Optometry Admission Test Practice Test

OAT - Optometry Admission Test Practice Test

OAT Biology Practice Test