when plants do not receive enough water their photosynthetic rate drops this is because

HESI A2

HESI A2 Biology Practice Test

1. When plants do not receive enough water, their photosynthetic rate drops. This is because:

A. water is a raw material for the light reactions in photosynthesis
B. carbon dioxide is not available
C. water provides the carbon atoms used to make sugar
D. not enough oxygen is produced to keep fermentation running

Correct answer: A

Rationale: When plants do not receive enough water, their photosynthetic rate drops because water is a raw material required for the light reactions in photosynthesis. In the light reactions, water is split to provide electrons, which are then utilized to produce energy carriers used in converting carbon dioxide into glucose during the Calvin cycle. Therefore, without sufficient water, the light reactions cannot proceed effectively, ultimately leading to a decrease in photosynthetic rate. Choice B is incorrect because carbon dioxide is a separate raw material needed for the Calvin cycle, not the light reactions. Choice C is incorrect as water provides electrons, not carbon atoms, for photosynthesis. Choice D is incorrect because fermentation is not directly related to photosynthesis; oxygen is produced during photosynthesis, not fermentation.

2. 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.

3. The force per unit area exerted against a surface by the weight of air above that surface in the Earth's atmosphere is the ______.

A. Atmospheric pressure
B. Barometric density
C. Aneroid pressure
D. Barometric pressure

Correct answer: A

Rationale: Atmospheric pressure is the correct term for the force per unit area exerted against a surface by the weight of air above that surface in the Earth's atmosphere. It is commonly measured in units such as pascals, millibars, or inches of mercury. Barometric density and aneroid pressure are not accurate descriptions for this phenomenon. Barometric density refers to the density of the atmosphere at a particular location, while aneroid pressure is linked to a type of barometer but not a comprehensive term for the force exerted by the weight of air.

4. What is the main function of the ribosomes in the cell?

A. DNA Replication
B. Protein Synthesis
C. Lipid Breakdown
D. Cell Division

Correct answer: B

Rationale: The correct answer is B: Protein Synthesis. Ribosomes are cellular organelles responsible for synthesizing proteins. This process is crucial for various cellular functions. Choice A, DNA Replication, is incorrect as ribosomes are not involved in this process. Choice C, Lipid Breakdown, is also incorrect as ribosomes do not play a role in lipid metabolism. Choice D, Cell Division, is incorrect as ribosomes are not directly involved in the process of cell division.

5. How many bones are included in the human skeletal system?

A. 412
B. 103
C. Over 300
D. 206

Correct answer: D

Rationale: There are 206 bones in the human skeletal system. This includes bones in the skull, spine, ribs, arms, legs, hands, and feet. The correct answer is 206 because that is the standard number of bones in an adult human body. Choices A, B, and C are incorrect as they do not reflect the accurate count of bones in the human skeletal system.