adaptive radiation refers to the evolutionary process where

ATI TEAS 7

TEAS 7 practice test science

1. Adaptive radiation refers to the evolutionary process where:

A. A single ancestral species diversifies into multiple descendant species due to ecological pressures in a heterogeneous environment.
B. Two unrelated species evolve similar adaptations in response to similar environments, leading to convergent evolution.
C. A population becomes increasingly well-adapted to its current environment through continued natural selection.
D. The fossil record exhibits gaps or missing links in the evolutionary history of a lineage.

Correct answer: A

Rationale: - Adaptive radiation is a process where a single ancestral species diversifies into multiple descendant species to exploit different ecological niches within a heterogeneous environment. - This diversification occurs due to the different selective pressures present in various habitats, leading to the evolution of distinct traits and adaptations in different descendant species. - Option A accurately describes the process of adaptive radiation, where the initial species undergoes rapid speciation to occupy different ecological roles and adapt to diverse environmental conditions. - Options B, C, and D do not accurately describe adaptive radiation but refer to other evolutionary processes such as convergent evolution, natural selection, and gaps in the fossil record, respectively.

2. Which of the following is NOT an example of a homeostatic mechanism?

A. Shivering when the body temperature falls.
B. Increasing heart rate when blood pressure is low.
C. Weight gain when consuming excess calories.
D. Secreting insulin to decrease blood sugar concentration.

Correct answer: C

Rationale: Weight gain when consuming excess calories is not an example of a homeostatic mechanism. Homeostasis refers to the body's ability to maintain a stable internal environment despite external changes. The other options listed (A, B, and D) involve physiological responses aimed at restoring balance or stability within the body (e.g., regulating body temperature, blood pressure, and blood sugar levels). Shivering, increasing heart rate, and secreting insulin are mechanisms to counteract specific imbalances and maintain internal equilibrium. In contrast, weight gain due to excess calorie intake does not represent a specific regulatory mechanism but rather an outcome of energy imbalance. The body stores excess energy as fat rather than actively regulating a physiological parameter to restore balance.

3. What causes varicose veins to occur?

A. Atherosclerosis.
B. Incompetent valves.
C. Loss of skin turgor.
D. Loss of blood vessel elasticity.

Correct answer: B

Rationale: Varicose veins occur when the valves within the veins become incompetent, leading to blood pooling in the veins instead of being efficiently pumped back to the heart. This causes the veins to become enlarged, twisted, and visible under the skin. Factors such as genetics, aging, pregnancy, and prolonged standing or sitting can contribute to the development of incompetent valves and the resulting varicose veins. Atherosclerosis is the buildup of plaque in arteries, not veins, and does not directly cause varicose veins. Loss of skin turgor is related to skin elasticity and not a direct cause of varicose veins. Loss of blood vessel elasticity is a general term and does not specifically address the mechanism behind varicose veins, which is primarily due to incompetent valves.

4. Salts like sodium iodide (NaI) and potassium chloride (KCl) use what type of bond?

A. Ionic bonds
B. Disulfide bridges
C. Covalent bonds
D. London dispersion forces

Correct answer: A

Rationale: Salts like sodium iodide (NaI) and potassium chloride (KCl) use ionic bonds. Ionic bonds are formed between atoms with significantly different electronegativities, leading to the transfer of electrons from one atom to another. In the case of NaI and KCl, sodium (Na) and potassium (K) are metals that easily lose electrons to become positively charged ions, while iodide (I) and chloride (Cl) are nonmetals that readily accept electrons to become negatively charged ions. The attraction between the oppositely charged ions forms the ionic bond, which holds the compound together in a lattice structure. Disulfide bridges (option B) are covalent bonds formed between sulfur atoms in proteins, not in salts. Covalent bonds (option C) involve the sharing of electrons between atoms and are typically seen in molecules, not ionic compounds like salts. London dispersion forces (option D) are weak intermolecular forces that occur between all types of molecules but are not the primary type of bond in salts like NaI and KCl.

5. Which of the following statements is not true about the relationship between the gastrointestinal system and the endocrine system?

A. Hormones signal to your body whether you are hungry or full.
B. Hormones regulate the amount of glucose in your blood.
C. Hormones stimulate digestive enzymes and peristalsis when you've eaten and need to digest food.
D. All of the above are true.

Correct answer: D

Rationale: The gastrointestinal system and the endocrine system are closely interconnected. Hormones released by the endocrine system play a crucial role in signaling hunger or fullness, regulating blood glucose levels, and stimulating digestive processes like enzyme secretion and peristalsis for efficient food digestion. Option D, stating 'All of the above are true,' is incorrect in the context of the question because there is a need to identify the statement that is not true about the relationship between the gastrointestinal system and the endocrine system. Choices A, B, and C are all correct statements that reflect the close relationship and interactions between the gastrointestinal and endocrine systems.