TEAS 7 science study guide free

TEAS 7 science study guide free Related

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The neutral theory of molecular evolution proposes that:

  • A. Most mutations in DNA are selectively neutral and do not affect an organism's fitness.
  • B. All mutations are beneficial and contribute to the adaptation of a population.
  • C. The rate of evolution is primarily driven by strong directional selection pressures.
  • D. Genetic drift plays a negligible role in shaping genetic variation within populations.
Correct Answer: A

Rationale: Rationale:
A) The neutral theory of molecular evolution, proposed by Motoo Kimura in the 1960s, suggests that the majority of mutations that occur in DNA are selectively neutral, meaning they do not have a significant impact on an organism's fitness. These neutral mutations are not subject to natural selection and are allowed to accumulate in populations over time. This theory helps explain the high levels of genetic variation observed within populations.

B) Option B is incorrect because not all mutations are beneficial. Mutations can be neutral, harmful, or beneficial, and the neutral theory specifically focuses on the idea that many mutations are neutral in their effects.

C) Option C is incorrect because the neutral theory suggests that evolution is not primarily driven by strong directional selection pressures. Instead, it emphasizes the role of genetic drift and the accumulation of neutral mutations in shaping genetic variation.

D) Option D is incorrect because

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Which enzyme breaks down carbohydrates like starches and sugars in the mouth?

  • A. Pepsin
  • B. Lipase
  • C. Amylase
  • D. Trypsin
Correct Answer: C

Rationale: The correct answer is Amylase. Amylase is the enzyme responsible for breaking down carbohydrates like starches and sugars in the mouth. Pepsin is a digestive enzyme that breaks down proteins in the stomach, lipase breaks down fats, and trypsin is another enzyme that breaks down proteins in the small intestine. Therefore, choices A, B, and D are incorrect for this question.

Which mineral is crucial for bone strength and is stored in bones and teeth?

  • A. Calcium
  • B. Iron
  • C. Magnesium
  • D. Potassium
Correct Answer: A

Rationale: Calcium is crucial for bone strength as it is a major mineral stored in bones and teeth. It plays a vital role in maintaining bone density and strength, making it essential for overall bone health. Calcium is essential for various physiological functions, including muscle contraction, nerve transmission, and blood clotting. Inadequate calcium intake can lead to conditions like osteoporosis, where bones become weak and brittle. Iron (Choice B) is important for transporting oxygen in the blood, but it is not stored in bones and does not play a significant role in bone strength. Magnesium (Choice C) is essential for bone health, but it is not primarily stored in bones and teeth. Potassium (Choice D) is crucial for various physiological functions, such as fluid balance and muscle function, but it is not a major mineral stored in bones and teeth for bone strength.

What is the rigid structure that provides shape and support to plant cells?

  • A. Cell wall
  • B. Plasma membrane
  • C. Nucleus
  • D. Cytoplasm
Correct Answer: A

Rationale: The correct answer is the cell wall, as it is the rigid structure that provides shape and support to plant cells. The cell wall is located outside the plasma membrane and is primarily composed of cellulose, giving it its rigid nature. The plasma membrane (option B) is a semi-permeable membrane surrounding the cell that regulates the movement of substances in and out of the cell. The nucleus (option C) houses the cell's genetic material and controls cellular activities. Cytoplasm (option D) is the gel-like substance within the cell that surrounds organelles and where various cellular processes take place, but it does not provide the rigid structure and support that the cell wall does.

Which hormone, produced by the pancreas, acts in opposition to insulin by increasing blood sugar levels?

  • A. Insulin
  • B. Glucagon
  • C. Cortisol
  • D. Thyroxine
Correct Answer: B

Rationale: Glucagon is the correct answer. Produced by the pancreas, glucagon acts in opposition to insulin by increasing blood sugar levels. Glucagon promotes the breakdown of glycogen into glucose in the liver, leading to the release of glucose into the bloodstream. Insulin, on the other hand, lowers blood sugar levels by facilitating the uptake of glucose into cells. Cortisol is a hormone produced by the adrenal glands, not the pancreas, and is involved in stress response and metabolism. Thyroxine is a hormone produced by the thyroid gland and is primarily responsible for regulating metabolism.

What is the body's primary defense against pathogens?

  • A. Phagocytes
  • B. Antibodies
  • C. Memory B cells
  • D. T lymphocytes
Correct Answer: A

Rationale: The correct answer is A: Phagocytes. Phagocytes are the body's first line of defense against pathogens. They are innate immune cells that engulf and digest foreign particles like bacteria and viruses, preventing infections. Phagocytes act as the initial barrier to invading pathogens and are part of the innate immune response. Choice B, Antibodies, are produced by B cells in the adaptive immune response. Choice C, Memory B cells, are also part of the adaptive immune response and provide a faster and stronger response upon re-exposure to pathogens. Choice D, T lymphocytes, are part of the adaptive immune response, particularly involved in cell-mediated immunity.

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