how do organisms maintain homeostasis

ATI TEAS 7

ATI TEAS Science

1. How do organisms maintain homeostasis?

A. By increasing their body temperature, blood pH, and fluid balance.
B. By undergoing biochemical processes and absorbing energy to increase entropy.
C. By undergoing biochemical processes to maintain the order of their external environment.
D. By using free energy and matter via biochemical processes to work against entropy.

Correct answer: D

Rationale: Organisms maintain homeostasis by utilizing free energy and matter through biochemical processes to counteract entropy, which helps in preserving internal stability. This process involves maintaining a balance within the organism's internal environment despite external changes, ensuring proper functioning and survival. Choice A is incorrect because increasing body temperature, blood pH, and fluid balance alone do not define the comprehensive process of maintaining homeostasis. Choice B is incorrect as absorbing energy to increase entropy goes against the concept of maintaining internal stability. Choice C is incorrect as maintaining the order of the external environment does not directly contribute to the organism's internal stability and balance.

2. How does the acceleration of an object change if the force acting on it is doubled?

A. Acceleration is halved
B. Acceleration doubles
C. Acceleration remains unchanged
D. Acceleration quadruples

Correct answer: B

Rationale: According to Newton's second law of motion, acceleration is directly proportional to the force acting on an object. When the force acting on an object is doubled, the acceleration of the object will also double. This relationship is described by the formula F = ma, where F is the force applied, m is the mass of the object, and a is the acceleration. Therefore, an increase in force will result in a proportional increase in acceleration. Choice A is incorrect because acceleration does not halve but doubles when force doubles. Choice C is incorrect as acceleration changes in direct proportion to force. Choice D is incorrect as acceleration does not quadruple but doubles when force doubles.

3. Which type of cell has a nucleus but lacks membrane-bound organelles?

A. Plant cell
B. Prokaryotic cell
C. Animal cell
D. Fungal cell

Correct answer: B

Rationale: The correct answer is B: Prokaryotic cell. Prokaryotic cells are characterized by having a nucleus that is not enclosed within a membrane (nuclear envelope) and lacking membrane-bound organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus. Plant, animal, and fungal cells are eukaryotic cells, which have a true nucleus enclosed within a nuclear envelope and contain membrane-bound organelles. Therefore, options A, C, and D are incorrect as they all represent eukaryotic cells that possess membrane-bound organelles.

4. What is the strongest evidence for evolution?

A. The fossil record
B. Comparative anatomy
C. Biogeography
D. All of the above

Correct answer: D

Rationale: A) The fossil record provides evidence of how organisms have changed over time, showing transitional forms and the progression of species. B) Comparative anatomy involves studying the similarities and differences in the structures of different species, which can reveal common ancestry and evolutionary relationships. C) Biogeography examines the distribution of species around the world, which can be explained by evolution and continental drift. By considering all of the above evidence together, scientists can build a comprehensive understanding of evolution and how species have changed and diversified over time.

5. Which hormone, produced by the thyroid gland, plays a key role in regulating calcium levels in the blood by promoting calcium release from bones and increasing calcium reabsorption in the kidneys?

A. Calcitonin
B. Parathyroid hormone (PTH)
C. Thyroxine
D. Insulin

Correct answer: A

Rationale: Calcitonin, produced by the thyroid gland, is responsible for regulating calcium levels in the blood. It works by decreasing blood calcium levels through two main mechanisms: promoting calcium uptake by bones and decreasing calcium reabsorption in the kidneys. Parathyroid hormone (PTH), on the other hand, increases blood calcium levels by promoting calcium release from bones and increasing calcium absorption in the intestines. Thyroxine, another thyroid hormone, primarily regulates metabolism and has no direct influence on calcium levels. Insulin, produced by the pancreas, is involved in regulating blood sugar levels and is not related to calcium homeostasis.