Nokea
Which of the following structures is found in the nucleus of a cell?
- A. Mitochondria
- B. Endoplasmic reticulum
- C. Chromosomes
- D. Ribosomes
Correct Answer: C
Rationale: Chromosomes, which contain genetic information, are found in the nucleus of a cell. They play a crucial role in cell division, gene expression, and inheritance. Mitochondria, responsible for energy production, are located in the cytoplasm, not the nucleus. The endoplasmic reticulum is mainly involved in protein and lipid synthesis and is not a component of the nucleus. Ribosomes, essential for protein synthesis, are found in the cytoplasm and on the endoplasmic reticulum, but not in the nucleus.
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Which of the following is best identified as a hypothesis?
- A. The environmental temperature can affect the growth of a plant's root.
- B. Plants need light to grow.
- C. A colder environment produces longer roots.
- D. Plants need 60 days to grow their roots.
Correct Answer: A
Rationale: Choice A is the best example of a hypothesis as it presents a testable statement regarding the impact of environmental temperature on plant root growth. A hypothesis should be specific and capable of being tested through experimentation, which is demonstrated in choice A. Choice B is a general statement rather than a testable hypothesis. Choice C lacks specificity and does not clearly state a cause-and-effect relationship to be tested. Choice D provides a specific time frame but does not address a relationship that can be tested through experimentation, making it less suitable as a hypothesis compared to choice A.
Which of the following glands produces hormones that regulate metabolism?
- A. Adrenal gland
- B. Pituitary gland
- C. Thyroid gland
- D. Liver
Correct Answer: C
Rationale: The thyroid gland is responsible for producing hormones that play a crucial role in regulating metabolism. One of the key hormones produced by the thyroid gland is thyroxine, which directly influences the body's metabolic rate. Therefore, the correct answer is the thyroid gland. The adrenal gland produces hormones like adrenaline, which are associated with the stress response and not primarily metabolic regulation. The pituitary gland regulates various other hormones but is not primarily responsible for metabolic regulation. The liver has a role in metabolism, mainly in processes like detoxification and nutrient storage, but it is not a gland that primarily produces hormones for metabolic regulation, making it an incorrect choice in this context.
What is the primary function of the nervous system?
- A. To produce hormones
- B. To transmit electrical impulses
- C. To carry oxygen
- D. To transport nutrients
Correct Answer: B
Rationale: The correct answer is B: To transmit electrical impulses. The primary function of the nervous system is to transmit electrical impulses and coordinate body activities. While hormones are produced by the endocrine system, not the nervous system, oxygen transportation is mainly carried out by the respiratory system, and nutrient transport is primarily the role of the circulatory system. Therefore, choices A, C, and D are incorrect as they do not align with the primary function of the nervous system.
Which hormone is released by the adrenal glands in response to stress?
- A. Insulin
- B. Cortisol
- C. Adrenaline
- D. Glucagon
Correct Answer: C
Rationale: Adrenaline is the correct answer. It is released by the adrenal glands in response to stress to prepare the body for the 'fight or flight' response. Adrenaline increases heart rate, dilates airways, and mobilizes energy stores to help the body deal with the perceived threat. Insulin (Choice A) is produced by the pancreas to regulate blood sugar levels, not in response to stress. Cortisol (Choice B) is another hormone released by the adrenal glands in response to stress, but it primarily helps regulate metabolism and immune response. Glucagon (Choice D) is also produced by the pancreas to increase blood sugar levels when they are low, not by the adrenal glands in response to stress.
Which of the following enzymes is responsible for adding a nucleotide to a growing DNA chain?
- A. Helicase
- B. Ligase
- C. Nuclease
- D. Polymerase
Correct Answer: D
Rationale: The correct answer is Polymerase. Polymerase is the enzyme responsible for adding nucleotides to a growing DNA chain during DNA replication. Helicase unwinds the DNA double helix to separate the DNA strands for replication, Ligase joins DNA fragments together by catalyzing the formation of phosphodiester bonds between them, and Nuclease cuts or degrades DNA strands. Therefore, choices A, B, and C are incorrect in the context of adding nucleotides to a growing DNA chain.