Essay Quiz On Photosynthesis (Light & Dark Reactions)

1. Which is released as a byproduct of photosynthesis?

Carbon dioxide

Carbon

Oxygen

Water

During photosynthesis, plants use sunlight, water, and carbon dioxide to produce glucose (a type of sugar) and oxygen. Oxygen is released into the atmosphere as a byproduct of this process. This oxygen is essential for the survival of many organisms, including humans, as it is used for respiration. Therefore, the correct answer is oxygen.

Explanation

During photosynthesis, plants use sunlight, water, and carbon dioxide to produce glucose (a type of sugar) and oxygen. Oxygen is released into the atmosphere as a byproduct of this process. This oxygen is essential for the survival of many organisms, including humans, as it is used for respiration. Therefore, the correct answer is oxygen.

2. Why do we perceive chlorophyll as being green?

Because it is green.

Because it absorbs green light.

Because it reflects green light.

Because it absorbs yellow light.

Chlorophyll is perceived as green because it reflects green light. When light hits chlorophyll molecules, they absorb certain wavelengths of light, mainly blue and red, and reflect or transmit the rest. The green wavelength is not efficiently absorbed by chlorophyll, so it is reflected back, giving chlorophyll its green color. This is why plants appear green to our eyes.

Explanation

Chlorophyll is perceived as green because it reflects green light. When light hits chlorophyll molecules, they absorb certain wavelengths of light, mainly blue and red, and reflect or transmit the rest. The green wavelength is not efficiently absorbed by chlorophyll, so it is reflected back, giving chlorophyll its green color. This is why plants appear green to our eyes.

3. Which would you expect to increase the rate of photosynthesis?

Incresing the carbon dioxide concentration

Decreasing the intensity of exposure to red light

Increasing the oxygen concentration

Decreasing the duration of exposure to red light

Increasing the carbon dioxide concentration is expected to increase the rate of photosynthesis because carbon dioxide is one of the essential components needed for the process. During photosynthesis, plants use carbon dioxide along with sunlight and water to produce glucose and oxygen. By increasing the carbon dioxide concentration, there will be more available for the plants to utilize, leading to an increase in the rate of photosynthesis. This is why increasing carbon dioxide levels is often considered beneficial for plant growth in controlled environments such as greenhouses.

Explanation

Increasing the carbon dioxide concentration is expected to increase the rate of photosynthesis because carbon dioxide is one of the essential components needed for the process. During photosynthesis, plants use carbon dioxide along with sunlight and water to produce glucose and oxygen. By increasing the carbon dioxide concentration, there will be more available for the plants to utilize, leading to an increase in the rate of photosynthesis. This is why increasing carbon dioxide levels is often considered beneficial for plant growth in controlled environments such as greenhouses.

4. Which could be used to monitor the rate of photosynthesis in a plant?

Carbon dioxide production

Water production

Oxygen production

Hydrogen production

Oxygen production can be used to monitor the rate of photosynthesis in a plant because during photosynthesis, plants convert carbon dioxide and water into glucose and oxygen. The oxygen produced is released into the atmosphere, and its rate of production can be measured to determine the rate of photosynthesis. Therefore, monitoring the amount of oxygen being produced can provide information about the efficiency and rate of photosynthesis in a plant.

Explanation

Oxygen production can be used to monitor the rate of photosynthesis in a plant because during photosynthesis, plants convert carbon dioxide and water into glucose and oxygen. The oxygen produced is released into the atmosphere, and its rate of production can be measured to determine the rate of photosynthesis. Therefore, monitoring the amount of oxygen being produced can provide information about the efficiency and rate of photosynthesis in a plant.

5. Which best describes the activity of autotrophs?

They use sunlight to break down large complex, energy-rich organic molecules

They convert carbon dioxide and water into complex, energy-rich organic molecules

They use the energy harvested by other photosynthesizers

The use the energy harvest by heterotrophs

Autotrophs are organisms that can produce their own food using energy from the environment. The correct answer states that autotrophs convert carbon dioxide and water into complex, energy-rich organic molecules. This process is known as photosynthesis, where autotrophs use sunlight as the energy source to convert inorganic molecules into organic molecules, such as glucose. This process is essential for the production of food and energy in autotrophic organisms.

Explanation

Autotrophs are organisms that can produce their own food using energy from the environment. The correct answer states that autotrophs convert carbon dioxide and water into complex, energy-rich organic molecules. This process is known as photosynthesis, where autotrophs use sunlight as the energy source to convert inorganic molecules into organic molecules, such as glucose. This process is essential for the production of food and energy in autotrophic organisms.

6. Which best describes light-independent reactions?

They are the first stage of photosynthesis.

They utilize the energy stored in ATP and NADPH.

They use carbon dioxide to synthesize proteins.

They create energy-rich ATP and NADPH.

Light-independent reactions, also known as the Calvin cycle, occur in the second stage of photosynthesis. These reactions do not require light and instead utilize the energy stored in ATP and NADPH, which are produced during the light-dependent reactions. In the Calvin cycle, carbon dioxide is used to synthesize sugars and other organic molecules, not proteins. Therefore, the correct answer is "They utilize the energy stored in ATP and NADPH."

Explanation

Light-independent reactions, also known as the Calvin cycle, occur in the second stage of photosynthesis. These reactions do not require light and instead utilize the energy stored in ATP and NADPH, which are produced during the light-dependent reactions. In the Calvin cycle, carbon dioxide is used to synthesize sugars and other organic molecules, not proteins. Therefore, the correct answer is "They utilize the energy stored in ATP and NADPH."