Nokea
Which type of technological device mimics the human body's innate ability to maintain homeostasis?
- A. Thermostat.
- B. Cell phone.
- C. Vacuum cleaner.
- D. Electric iron.
Correct Answer: A
Rationale: The correct answer is A: Thermostat. A thermostat mimics the human body's ability to maintain homeostasis by regulating temperature to keep it within a narrow range. The human body also maintains internal balance through various physiological mechanisms. The other choices (B: Cell phone, C: Vacuum cleaner, D: Electric iron) do not relate to maintaining homeostasis. Cell phones are communication devices, vacuum cleaners clean surfaces, and electric irons press clothing. Only a thermostat is designed to monitor and adjust temperature to maintain a stable internal environment, similar to the body's homeostatic mechanisms.
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Select the cell parts that are present in plant cells but not animal cells (there may be more than one answer):
- A. Cell membrane
- B. Cell wall
- C. Ribosome
- D. Chloroplast
Correct Answer: D
Rationale: Chloroplasts are unique to plant cells and are responsible for photosynthesis, a process that converts light energy into chemical energy. Animal cells do not contain chloroplasts as they do not perform photosynthesis. Therefore, the correct answer is D - Chloroplast. The cell membrane is found in both plant and animal cells, serving as a protective barrier, while the cell wall is a rigid structure present in plant cells that provides support and protection. Ribosomes are cellular structures responsible for protein synthesis and are present in both plant and animal cells.
Which term means the movement of water across a semi-permeable membrane from a low solute concentration to a high solute concentration?
- A. Active Transport.
- B. Passive Transport.
- C. Osmosis.
- D. Diffusion.
Correct Answer: C
Rationale: The correct answer is C: Osmosis. Osmosis is the movement of water molecules across a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration. This process occurs passively, without the need for energy input.
Rationale:
1. Osmosis specifically refers to the movement of water molecules.
2. It occurs across a semi-permeable membrane.
3. The direction of movement is from low solute concentration to high solute concentration.
4. Osmosis is a passive transport process, as it does not require energy.
Summary:
A: Active Transport involves the movement of molecules against the concentration gradient, requiring energy input.
B: Passive Transport includes processes like diffusion and osmosis but does not involve active energy expenditure.
D: Diffusion is the movement of molecules from high concentration to low concentration, not specific to water movement across a membrane.
What type of bond in the base of the DNA nucleotides holds the strands together?
- A. Hydrogen.
- B. Sodium chloride.
- C. Copper.
- D. Potassium bromide.
Correct Answer: A
Rationale:
Which of the following statements is not true about enzymes?
- A. They catalyze reactions
- B. They raise the activation energy needed
- C. They have an active site
- D. They are typically proteins
Correct Answer: B
Rationale: Enzymes function by lowering the activation energy required for a reaction to occur, not by raising it. This catalytic property allows enzymes to accelerate reactions without being consumed in the process. Enzymes are biological catalysts that are typically proteins and have specific active sites where substrates bind and reactions take place. The statement that enzymes raise the activation energy needed is incorrect as their role is to lower this energy barrier. Therefore, the correct answer is B.
A scientist needs 12 mL of a solution. They have a bottle with 0.12L in it. Do they have enough?
- A. Yes, they have exactly what they need
- B. Yes, they have more than what they need
- C. No, they do not have enough
- D. None of the above
Correct Answer: B
Rationale: To accurately compare the quantities, it is important to convert both to the same unit. As 1L is equal to 1000 mL, the bottle contains 120 mL (0.12L x 1000 mL/L). Since the scientist only needs 12 mL, it is evident that they have more than enough solution in the bottle, making choice B the correct answer.