Question 1

In this drawing of a chloroplast,which structure represents the thylakoid membrane?

Accepted Answer

The answer of In this drawing of a chloroplast,which structure...

Question 2

Autotrophs that utilize light as their energy source are

Accepted Answer

Photoautotrophs are organisms that produce their own food using light energy. Examples include plants, algae, and some bacteria. Fungi are not autotrophs, but rather heterotrophs that obtain their energy by consuming other organisms or organic matter. Heterotrophs also do not utilize light as their energy source. Chemosynthetic autotrophs obtain their energy from chemical reactions, usually involving inorganic compounds, rather than light.

Question 3

In photophosphorylation,energy from electron flow is used to transport from the to the thylakoid compartment,generating a concentration gradient of .

Accepted Answer

In photophosphorylation, energy from electron flow is used to transport H+ ions from the stroma into the thylakoid compartment, creating a proton gradient (H+ concentration gradient) across the thylakoid membrane.

Question 4

Where is chlorophyll found in a plant cell?

Accepted Answer

Chlorophyll is found in thylakoid membranes which are part of the chloroplasts in plant cells.

Question 5

In the chloroplast,sugars are made in a compartment that is filled with a thick fluid called the

Accepted Answer

The compartment in the chloroplast where sugars are made is the stroma, which is filled with a thick fluid. The matrix is a term used to describe the inner compartment of the mitochondria. Stomata are tiny pores on the surface of leaves that allow for gas exchange. Thylakoids are flattened, membrane-bound sacs that are involved in the light-dependent reactions of photosynthesis.

Question 6

Which of the following molecules is both a reactant and a product of photosynthesis?

Accepted Answer

H2O is a reactant in the light reactions of photosynthesis, where it is split to provide electrons for the electron transport chain. Oxygen is released as a product of this reaction. In the following Calvin cycle, the electrons from this reaction are used to reduce carbon dioxide to form glucose, making H2O a product of photosynthesis as well. Glucose is not a reactant in photosynthesis, but rather the product of the Calvin cycle. Chlorophyll is a pigment involved in photosynthesis, but is not a reactant or product.

Question 7

The electrons lost from the reaction center of photosystem II are replaced by electrons from

Accepted Answer

The electrons lost from the reaction center of photosystem II are replaced by electrons from water (H2O), which is split through a process called photolysis. This process releases oxygen as a byproduct and provides electrons to replace those lost in photosystem II.

Question 8

What is the main adaptive advantage of the C4 and CAM photosynthesis strategies over the C3 strategy?

Accepted Answer

The main adaptive advantage of both C4 and CAM photosynthesis strategies over the C3 strategy is the ability to conserve water and synthesize glucose efficiently under hot, dry conditions. C4 and CAM photosynthesis strategies both have specialized pathways that store CO2 until it is needed for the Calvin cycle, allowing the plant to keep their stomata closed and conserve water. This is especially advantageous in hot, dry conditions where water is scarce. In contrast, C3 plants do not have specialized pathways to conserve water and are less efficient at producing glucose in hot, dry conditions. Therefore, C is the best answer.

Question 9

Ozone consists of _ _ oxygen atom(s).

Accepted Answer

Ozone is a molecule made up of three oxygen atoms, represented chemically as O3.

Question 10

CO2 enters and O2 escapes from a leaf via

Accepted Answer

CO2 enters a leaf and O2 escapes from a leaf through stomata. Stomata are tiny pores on the surface of a leaf that allow gases, including CO2 and O2, to diffuse in and out of the plant. The stroma, grana, and thylakoids are all parts of a chloroplast, which is where photosynthesis occurs, but they are not the site of gas exchange.

Question 11

Which of the following has been a major source of ozone destruction over the past 50 years?

Accepted Answer

Chlorofluorocarbons (CFCs) have been identified as a major source of ozone destruction over the past 50 years. CFCs were commonly used in refrigerants, solvents, foam-blowing agents, and aerosol propellants until they were phased out under the Montreal Protocol in 1987. CFCs break down in the atmosphere and release chlorine, which can then react with ozone, breaking it down into oxygen molecules. This reaction has been a major contributor to the depletion of the ozone layer.

Question 12

To produce one glucose,the Calvin cycle needs to be run through time(s).

Accepted Answer

The Calvin cycle must turn six times to fix six carbon atoms, which are needed to produce one glucose molecule (C6H12O6). Each turn fixes one carbon atom.

Question 13

A packet of light energy is called a

Accepted Answer

A packet of light energy is called a photon. This is a basic concept in quantum mechanics and is widely used in the study of light and its interactions with matter.

Question 14

In most green plants,chloroplasts are

Accepted Answer

Chloroplasts are concentrated in a zone of leaf tissue called the mesophyll, which is responsible for photosynthesis. This area contains the majority of the chloroplasts in a plant cell.

Question 15

Which of the following is part of the light reaction?

Accepted Answer

Formation of waste products in the form of O2 is part of the light reaction. The light reaction is responsible for the generation of ATP and NADPH, and the release of molecular oxygen (O2) as a waste product. Choices A, B, and D are part of the Calvin Cycle, which is the dark reaction or the light-independent reaction.

Question 16

Which of the following are produced during the Calvin cycle?

Accepted Answer

The products of the Calvin cycle are glucose (sugar), ADP (which is converted back into ATP in the light-dependent reactions), and NADP+ (which is converted back into NADPH in the light-dependent reactions). ATP and NADPH are actually consumed, not produced, during the Calvin cycle. O2 is a product of photosynthesis but not specifically the Calvin cycle. CO₂ and ⁺ are not relevant to the Calvin cycle.

Question 17

It has been argued that cutting old- growth forests and replacing them with plantations of young trees would help to alleviate the threat of global greenhouse warming.What important fact does this argument ignore?

Accepted Answer

Cutting old-growth forests would release the carbon stored in the biomass of those trees into the atmosphere as CO2, which would exacerbate the problem of global greenhouse warming. While young trees do absorb CO2 from the atmosphere as they grow, it takes many years for them to reach the same level of biomass as mature old-growth trees, so replanting with young trees would not immediately offset the carbon released by cutting down the old-growth forests. Additionally, marine algae do play a significant role in global CO2 dynamics, but this does not negate the importance of forests as carbon sinks.

Question 18

Plant cells are protected from the harmful effects of reactive oxidative molecules by

Accepted Answer

Carotenoids act as antioxidants and protect plant cells from the damaging effects of reactive oxygen species. Mitochondria produce reactive oxygen species as a byproduct of respiration, while chlorophyll and ATP are not directly involved in protecting cells from reactive oxidative molecules.

Question 19

Plants use sugars as

Accepted Answer

Plants use sugars as a fuel for cellular respiration and as a starting material for making other organic molecules, such as cellulose or starch. This provides energy for the plant to carry out its metabolic processes and to grow. While sugars are initially produced through photosynthesis, they are primarily utilized by the plant for cellular respiration and biosynthesis rather than as a direct source of fuel for photosynthesis or for the Calvin cycle.

Question 20

Global warming due to the greenhouse effect may be

Accepted Answer

Photosynthesis is the natural process by which plants convert CO2 to oxygen, thereby reducing the amount of CO2 in the atmosphere. Therefore, photosynthesis can help moderate the greenhouse effect and mitigate global warming. Burning of fossil fuels (option A) actually adds more CO2 to the atmosphere, exacerbating the problem. Global warming is not a natural part of the planet's cycle (option B), but rather a result of human activities. Option C is incorrect because photosynthesis removes CO2, not adds it.

Quiz 7: Photosynthesis: Using Light to Make Food