what is the basic unit of life
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HESI A2

HESI A2 Biology Practice Test 2024

1. What is the fundamental unit of life?

Correct answer: B

Rationale: The correct answer is 'B: Cell.' Cells are indeed the fundamental unit of life as they are responsible for all living functions, including growth, reproduction, and maintaining homeostasis. While atoms are the basic building blocks of matter, cells are the smallest structural and functional unit of living organisms. Choices C and D, tissue and organ respectively, are composed of multiple cells working together and are not considered the basic unit of life.

2. What kind of symbiosis exists between a pneumonia bacterium and a human?

Correct answer: B

Rationale: In the case of a pneumonia bacterium and a human, the relationship is best described as parasitism. The bacterium benefits by causing harm to the human host, while the human is negatively affected by the presence of the bacterium, leading to illness or infection. This is a classic example of a parasitic relationship where one organism benefits at the expense of the other. Mutualism (Choice A) is a type of symbiotic relationship where both organisms benefit from each other. Commensalism (Choice C) is a symbiotic relationship where one organism benefits, and the other is neither helped nor harmed. Competition (Choice D) refers to a relationship where both organisms are negatively affected by each other as they compete for resources.

3. Which of the following is a tertiary consumer?

Correct answer: A

Rationale: The correct answer is A, Owl. Tertiary consumers are organisms that feed on secondary consumers, which, in turn, feed on primary consumers. Owls are considered tertiary consumers because they primarily feed on animals such as rodents, which are secondary consumers. Shrew (choice B) is a secondary consumer, feeding on insects and worms, placing it at a lower trophic level than the owl. Grasshopper (choice C) is a primary consumer, feeding on plants. Wheat (choice D) is not a consumer in the food chain but a plant.

4. Which of the following arrangement is seen in the plasma membrane?

Correct answer: C

Rationale: The correct arrangement seen in the plasma membrane is proteins embedded in the lipid bilayer. The plasma membrane is composed of a lipid bilayer with embedded proteins. These proteins perform various functions such as transport, signaling, and structural support within the cell membrane. This arrangement allows for the selective permeability of the membrane and facilitates communication between the cell and its environment. Choices A, B, and D are incorrect because the primary arrangement in the plasma membrane involves proteins being embedded in the lipid bilayer, not lipids with embedded proteins, an outer and inner lipid layer, or altering protein and lipid layers.

5. Which type of passive transport uses proteins that change shape to move a target molecule through the membrane?

Correct answer: B

Rationale: The correct answer is B: Carrier proteins. Carrier proteins are involved in facilitated diffusion, a type of passive transport where specific target molecules are moved across the membrane with the help of proteins that change shape. These carrier proteins bind to the target molecule on one side of the membrane, undergo a conformational change, and then release the molecule on the other side. This process is crucial for the selective transport of certain molecules that cannot pass through the membrane by simple diffusion. Choices A and C are incorrect because diffusion and channel proteins do not involve proteins that change shape to transport target molecules selectively. Choice D is incorrect as carrier proteins fit the description provided in the question.

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