Nokea
Which of the following stimulates adaptive immunity?
- A. Peptides
- B. Phagocytes
- C. Prions
- D. Platelets
Correct Answer: C
Rationale: The correct answer is C: Prions. Prions are infectious proteins that can stimulate an adaptive immune response by triggering the production of specific antibodies. Peptides are fragments of proteins and can be processed and presented by antigen-presenting cells to activate T cells, which play a role in adaptive immunity. Phagocytes, such as macrophages, are part of the innate immune system and are involved in engulfing and destroying pathogens, but they do not directly stimulate adaptive immunity. Platelets are primarily involved in blood clotting and are not directly related to stimulating adaptive immunity.
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Which statement below correctly describes the movement of molecules in the body and in relation to the external environment?
- A. Osmosis is the movement of a solution from an area of low solute concentration to an area of high solute concentration.
- B. Diffusion is the process in which oxygen moves from the lungs into the bloodstream.
- C. Dissipation is the transport of molecules across a semipermeable membrane from low to high concentration.
- D. Reverse osmosis is the movement of molecules in a solution from high concentration to low concentration.
Correct Answer: B
Rationale: The correct answer is B. Diffusion is the process where molecules move from an area of higher concentration to an area of lower concentration. In the context of the lungs, oxygen moves from the alveoli in the lungs to the bloodstream through diffusion. Choice A is incorrect as osmosis involves the movement of water across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration. Choice C is incorrect because dissipation does not refer to a specific biological process related to molecule movement. Choice D is incorrect as reverse osmosis is a process where solvent moves from an area of high solute concentration to an area of low solute concentration, not the movement of molecules within a solution.
Which of the following is most different from the others?
- A. Thyroid gland
- B. Stomach
- C. Intestines
- D. Pancreas
Correct Answer: B
Rationale: The correct answer is B, 'Stomach.' The stomach is an organ of the digestive system responsible for breaking down food through mechanical and chemical digestion. In contrast, the thyroid, intestines, and pancreas are glands. The thyroid gland regulates metabolism through hormone secretion, the intestines aid in digestion and nutrient absorption, and the pancreas secretes digestive enzymes and hormones. Therefore, the stomach is functionally different from the other options as it is an organ involved in digestion, while the others are glands with specific secretory functions.
What correction should the student make to the hypothesis: Lengthening the string of the pendulum increases the time it takes the ball to make one complete period?
- A. Turn it into an 'if-then' statement.
- B. Change 'will increase' to 'increases.'
- C. Switch the order of the sentence so that the phrase about the period comes first.
- D. No corrections are needed.
Correct Answer: A
Rationale: The correct answer is A. A hypothesis should be structured as an 'if-then' statement for clarity. This format helps to clearly establish the relationship between the variables and the expected outcome. In this case, the student should frame the hypothesis in a way that if a specific action is taken (lengthening the string), then a specific outcome is expected (increasing the time it takes for the ball to make one complete period). 'If-then' statements are fundamental in hypothesis construction as they clearly define the cause and effect relationship being tested. Choice B is incorrect because changing 'will increase' to 'increases' does not address the structural issue of the hypothesis. Choice C is incorrect as switching the order of the sentence does not fundamentally alter the clarity of the hypothesis. Choice D is incorrect as the hypothesis structure can be improved for better understanding and testing, making correction necessary.
What type of chemical bond connects the oxygen and hydrogen atoms in a molecule of water?
- A. Static bond
- B. Aquatic bond
- C. Ionic bond
- D. Covalent bond
Correct Answer: D
Rationale: The correct answer is D, Covalent bond. Covalent bonds are formed between oxygen and hydrogen atoms in a water molecule. In a water molecule, each hydrogen atom forms a covalent bond with the oxygen atom, sharing electrons to achieve a stable configuration. Static bond (choice A) and Aquatic bond (choice B) are not valid types of chemical bonds. Ionic bond (choice C) involves the transfer of electrons between atoms of different electronegativities, which is not the case between oxygen and hydrogen in a water molecule.
Which of the following best describes a plane that divides the body into upper and lower portions?
- A. Coronal
- B. Transverse
- C. Oblique
- D. Median
Correct Answer: B
Rationale: The correct answer is B: Transverse. A transverse plane, also known as a horizontal plane, divides the body into upper and lower portions. This plane is perpendicular to the long axis of the body. Coronal planes divide the body into anterior and posterior portions. Oblique planes pass through the body at an angle, neither strictly horizontal nor vertical. The median plane passes longitudinally through the body, dividing it into equal left and right halves.