1. You design an experiment to test the effect of temperature on plant growth. Which variable should you keep constant?

A. The type of soil used.
B. The amount of sunlight the plants receive.
C. The amount of water given to the plants.
D. The temperature variations being tested.

Correct answer: A

Rationale: In this experiment, the variable being tested is the effect of temperature on plant growth. To ensure that any observed changes in plant growth are due to temperature variations and not other factors, it is important to keep other variables constant. The type of soil used can significantly impact plant growth, so it should be kept constant to isolate the effect of temperature. Keeping the amount of sunlight and water constant would also help ensure that any differences in plant growth are due to temperature variations.

2. Two coherent light waves with a slight phase difference interfere. What determines the resulting intensity of the combined wave?

A. The individual intensities of the waves
B. The wavelength of the waves
C. The distance between the waves
D. The color of the waves

Correct answer: A

Rationale: The intensity of the resulting wave depends on the individual intensities and the phase difference between the interfering waves. Constructive interference leads to higher intensity, while destructive interference leads to lower intensity.

3. Half-life refers to the characteristic time it takes for:

A. Radioactive intensity to completely disappear
B. The number of neutrons in a nucleus to double
C. The number of protons in a nucleus to change
D. An isotope to decay by half of its initial quantity

Correct answer: D

Rationale: The correct answer is D: An isotope to decay by half of its initial quantity. The half-life of a substance is the time it takes for half of the initial quantity of radioactive atoms to decay. This is a characteristic property of each radioactive isotope and is used to determine the rate of decay of a substance. Option A is incorrect because radioactive intensity does not completely disappear in half-life, it only decreases by half. Options B and C are unrelated to the concept of half-life and do not accurately describe its definition.

4. What is the myelin sheath and what does it do?

A. A group of nerve cells that perform a specific function.
B. A fatty substance that insulates some nerve fibers.
C. A fluid-filled cavity within the brain.
D. The junction between two neurons.

Correct answer: B

Rationale: The correct answer is B. The myelin sheath is a fatty substance that insulates some nerve fibers. It is essential for the proper functioning of the nervous system as it acts as an insulator, allowing for faster transmission of nerve impulses along the axon. Without the myelin sheath, nerve signals could be disrupted or weakened, leading to issues with movement, sensation, and other neurological functions. Options A, C, and D are incorrect as they do not accurately describe the myelin sheath or its function.

5. Which division of the nervous system is responsible for involuntary functions such as heart rate, digestion, and respiratory rate?

A. Somatic nervous system
B. Autonomic nervous system
C. Peripheral nervous system
D. Central nervous system

Correct answer: b

Rationale: The correct answer is B: Autonomic nervous system. The autonomic nervous system is responsible for regulating involuntary functions in the body, such as heart rate, digestion, respiratory rate, and other automatic processes. The somatic nervous system (A) controls voluntary muscle movements, the peripheral nervous system (C) consists of nerves outside the brain and spinal cord, and the central nervous system (D) includes the brain and spinal cord. Understanding the functions and divisions of the nervous system is crucial for grasping how different bodily processes are controlled and regulated.

6. Which of the following is a risk factor for developing kidney stones?

A. Consuming a diet rich in fruits and vegetables
B. Maintaining adequate hydration with water
C. Having a family history of kidney stones
D. Regularly engaging in moderate exercise

Correct answer: C

Rationale: Having a family history of kidney stones is a risk factor for developing them because genetics play a role in kidney stone formation. Individuals with a family history are more likely to inherit genetic factors that increase the likelihood of developing kidney stones. While consuming a diet rich in fruits and vegetables, maintaining adequate hydration with water, and regularly engaging in moderate exercise are generally healthy habits that can help prevent kidney stones, they are not direct risk factors for developing them. Therefore, option C, having a family history of kidney stones, is the correct answer.