a student was asked to count birds in a given location over a 24 hour period which count would make her data most valid

HESI A2

HESI A2 Biology 2024

1. A student was asked to count birds in a given location over a 24-hour period. Which count would make their data most valid?

A. Count birds at one feeder every 6 hours.
B. Count birds at three feeders at noon and 6:00 P.M.
C. Count birds at one feeder at noon and 6:00 P.M.
D. Count birds at three feeders every 6 hours.

Correct answer: C

Rationale: Counting birds at one feeder at consistent time intervals (noon and 6:00 P.M.) over a 24-hour period ensures that the data collected are evenly distributed and provide a more accurate representation of the bird population in that location throughout the day. This method allows for observations during different times of the day, capturing potential variations in bird activity and distribution. Choice A is not as effective as it lacks observations at different times of the day, potentially missing variations in bird behavior. Choice B involves multiple locations and times, which could introduce more variables and make it harder to analyze the data accurately. Choice D, counting birds at three feeders every 6 hours, may provide too frequent data points and not cover all significant time intervals for observing bird activity.

2. Which organelle is responsible for detoxifying harmful substances in the cell?

A. Endoplasmic Reticulum
B. Lysosomes
C. Peroxisomes
D. Golgi Apparatus

Correct answer: C

Rationale: The correct answer is C, Peroxisomes. Peroxisomes are responsible for detoxifying harmful substances in the cell by breaking down fatty acids and producing hydrogen peroxide. This process helps protect the cell from damage caused by toxic substances. Choice A, Endoplasmic Reticulum, is involved in protein and lipid synthesis, not detoxification. Choice B, Lysosomes, contain enzymes for digestion and waste removal, not primarily detoxification. Choice D, Golgi Apparatus, is responsible for modifying, sorting, and packaging proteins for secretion, not detoxification.

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

A. Lipids with embedded proteins
B. An outer lipid layer and an inner lipid layer
C. Proteins embedded in lipid bilayer
D. Altering protein and lipid layers

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.

4. Which of the following shows how information is transformed to make a protein?

A. DNA-RNA-protein
B. gene-chromosome-protein
C. ATP-amino acid-protein
D. RNA-DNA-protein

Correct answer: A

Rationale: The correct sequence of events for protein synthesis is that DNA is transcribed into RNA, which is then translated into a protein. This process is known as the central dogma of molecular biology. In this sequence, DNA serves as the template for RNA synthesis (transcription), and the RNA serves as the template for protein synthesis (translation). Choice B is incorrect as genes are segments of DNA that code for proteins, and chromosomes are structures that contain DNA. Choice C is incorrect as ATP is an energy molecule and amino acids are the building blocks of proteins, but they are not directly involved in the synthesis process. Choice D is incorrect because RNA is first transcribed from DNA and then used as a template to produce proteins.

5. Which of the following is not a product of the Krebs cycle?

A. carbon dioxide
B. oxygen
C. adenosine triphosphate (ATP)
D. energy carriers

Correct answer: B

Rationale: The correct answer is B: oxygen. Oxygen is not a product of the Krebs cycle. During the Krebs cycle, carbon dioxide, adenosine triphosphate (ATP), and energy carriers like NADH and FADH2 are produced. Carbon dioxide is a byproduct of the cycle, ATP is a form of energy produced, and energy carriers play a crucial role in transferring energy within the cell. Therefore, oxygen is the only option that is not a product of the Krebs cycle, making it the correct answer.