Q: A student is asked to calculate the partial pressure of oxygen ($$P_{O_2$}) in $$air at sea level, where atmospheric pressure is 760 mmHg and oxygen makes up 21% of the atmosphere. Which equation should they use, and what is the correct answer?

$$P_{O_2$} = 0.21 \times 760 = 159.6$$ mmHg

Question 1

Which of the following best explains why fungi are critical to the carbon cycle in terrestrial ecosystems?

Accepted Answer

Fungi break down lignin and cellulose in dead plant material, releasing CO$$_2$$ through cellular respiration.

Question 2

A paleontologist discovers a sedimentary rock layer containing a unique fossil species that is found only in rocks of a specific age worldwide. This fossil is most likely:

Accepted Answer

An index fossil

Question 3

Which of the following statements correctly compares ectomycorrhizal fungi (EMF) and arbuscular mycorrhizal fungi (AMF)?

Accepted Answer

AMF form highly branched structures inside root cells, while EMF form sheaths around roots and grow between root cells.

Question 4

Which animal group is characterized by a segmented body and jointed appendages?

Accepted Answer

Arthropoda

Question 5

A researcher is studying an animal with bilateral symmetry, three germ layers, and a body cavity completely lined with mesoderm. This animal is best described as:

Accepted Answer

A triploblastic coelomate

Question 6

Which of the following best describes the relationship between body size and basal metabolic rate (BMR) per unit of body mass in mammals?

Accepted Answer

As body size increases, BMR per unit of body mass decreases.

Question 7

Which mechanism of heat exchange is primarily responsible for a lizard warming itself on a sunlit rock?

Accepted Answer

Radiation

Question 8

Marine bony fishes face which of the following osmoregulatory challenges, and how do they compensate?

Accepted Answer

They lose water by osmosis and drink seawater, excreting excess salts through their gills.

Question 9

Which part of the mammalian nephron is primarily responsible for creating a concentration gradient in the renal medulla, allowing for the production of concentrated urine?

Accepted Answer

Loop of Henle

Question 10

A student is asked to calculate the partial pressure of oxygen ($$P_{O_2$}) in $$air at sea level, where atmospheric pressure is 760 mmHg and oxygen makes up 21% of the atmosphere. Which equation should they use, and what is the correct answer?

Accepted Answer

$$P_{O_2$} = 0.21 	imes 760 = 159.6$$ mmHg

Question 11

Which of the following best explains why gas exchange in bird lungs is more efficient than in mammalian lungs?

Accepted Answer

Birds have unidirectional airflow through their lungs, maintaining a constant high oxygen gradient.

Question 12

The following reversible reaction is important in blood pH regulation: $$\mathrm{CO_2$ + H_2O \rightleftharpoons $$HCO_3$$^- + H^+}. $$What happens to blood pH if CO$$_2$$ levels increase?

Accepted Answer

Blood pH decreases (becomes more acidic) due to increased H$$^+$$ concentration.

Question 13

Which of the following best describes the role of the sodium–potassium pump (Na$$^+/K$^+-$$ATPase) in maintaining the resting membrane potential of a neuron?

Accepted Answer

It pumps 3 Na$$^+$$ out and 2 K$$^+ in$$, creating a net negative charge inside the cell.

Question 14

Which of the following is a key advantage of complete metamorphosis in insects compared to incomplete metamorphosis?

Accepted Answer

Larvae and adults occupy different ecological niches, reducing competition for resources.

Question 15

Which of the following best describes the difference between the afferent and efferent divisions of the peripheral nervous system (PNS)?

Accepted Answer

Afferent neurons carry signals from sensory receptors to the CNS; efferent neurons carry signals from the CNS to effectors.

Question 16

A patient is diagnosed with diabetes insipidus, a condition in which the body cannot properly respond to antidiuretic hormone (ADH). Which of the following symptoms would you expect?

Accepted Answer

Production of large volumes of dilute urine and dehydration

Question 17

Which of the following best describes the difference between oviparity, ovoviviparity, and viviparity?

Accepted Answer

Viviparous animals develop embryos inside the mother with direct nourishment; oviparous animals lay eggs; ovoviviparous animals retain eggs internally without direct nourishment.

Question 18

Which of the following is an example of negative feedback maintaining homeostasis?

Accepted Answer

A rise in blood glucose triggers insulin release, which lowers blood glucose levels.

Question 19

Which of the following best explains why myelination increases the speed of action potential propagation along an axon?

Accepted Answer

Myelin insulates the axon, allowing action potentials to 'jump' between nodes of Ranvier in a process called saltatory conduction.

BIO 201 Exam 3 Study Guide: Fungi, Animal Diversity, Physiology, and Development

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