Unit 2 cell energy (photosynthesis & cellular respiration) 2023n

Stomata are tiny openings found in plant leaves. Specialized cells known as guard cells surround the stomata and open and close the openings. When it is very hot, plants may close their stomata to prevent water loss. When plants close their stomata, what else is affected?

• Plants cannot take in water from the air

• Plants cannot release glucose made in photosynthesis

• Plants cannot take in the sunlight they need for photosynthesis

• Plants cannot take in the carbon dioxide they need for photosynthesis

Answer explanation

The stomata are where plants are able to take in CO₂ and release the O₂ produced in photosynthesis. Closing the stomata can prevent water loss through leaves, but it also prevents taking in CO₂ necessary for photosynthesis.

Examine the model for two cellular organelles found in many eukaryotic cells. Which molecule(s) could be represented by the circle labeled Z that is produced as an output of the mitochondria and required by the chloroplast? Select ALL that apply.

• Letter Z could be a water molecule because it is produced in cellular respiration and is a reactant of photosynthesis.

• Letter Z could be a water molecule because it is produced in photosynthesis and is a reactant of cellular respiration.

• Letter Z could be a glucose molecule because it is produced in photosynthesis and is a reactant of cellular respiration.

• Letter Z could be an oxygen molecule because it is produced in cellular respiration and is a reactant of photosynthesis.

• Letter Z could be carbon dioxide because it is produced in cellular respiration and is a reactant of photosynthesis.

Answer explanation

Carbon dioxide and water are produced in cellular respiration as byproducts since the main purpose of cellular respiration is ATP production. The reactants of cellular respiration are the products of photosynthesis. Inversely, the products of cellular respiration are the reactants of photosynthesis.

Review the schematic diagram of photosynthesis and the involvement of the chloroplast in this process. All BUT ONE choice describes what is happening in the light dependent reaction.

• Reactants include carbon dioxide and water.

• Water is broken down and oxygen is produced.

• Energy from sunlight is absorbed by chlorophyll.

• Products include ATP and NADPH.

Answer explanation

Reactants include carbon dioxide and water. This is true for the entire process of photosynthesis, but not the light dependent reaction, which takes places in the thylakoid membranes.

Evergreen needles have a thick outer coating, called a cuticle. Predict how this provides an advantage for photosynthesis.

• The cuticle helps keep the tree cooler.

• The cuticle allows them to retain more water.

• The cuticle allows for enhanced gas exchange.

• The cuticle holds in more glucose.

Answer explanation

The cuticle is waxy, repelling water and preventing water loss from leaves and needles. This helps conserve the water needed for photosynthesis.

Evergreen needles have a thick outer coating, called a cuticle. Predict how this provides an advantage for photosynthesis.

• The cuticle helps keep the tree cooler.

• The cuticle allows them to retain more water.

• The cuticle allows for enhanced gas exchange.

• The cuticle holds in more glucose.

Answer explanation

The cuticle is waxy, repelling water and preventing water loss from leaves and needles. This helps conserve the water needed for photosynthesis.

The chemical process for respiration.

• releases oxygen.

• releases energy

• releases glucose

• releases adp

Answer explanation

Respiration takes in glucose, oxygen, and ADP and releases energy.

Lilly and her lab partner, Alberto are investigating factors that influence the rate of photosynthesis. They know that any change to the reactants in photosynthesis could have an effect on the production of glucose and oxygen. In doing some research, the pair comes across the data shown above. They decide to brainstorm possible variables they could change in their experiment that could increase the rate of photosynthesis. Evaluate their list of possibilities. Based on the data and your knowledge of photosynthesis, what would you advise Lilly and Alberto to consider changing in their experiment if they wanted to increase the rate of photosynthesis? Choose ALL that apply.

• Place the plants in an oxygen rich environment.

• Place the plant under a green light.

• Place the plant under a red light.

• Place the plants in a carbon dioxide rich environment.

• Place the plants under a blue light.

Answer explanation

According to the graph, red and blue are both wavelengths that provide the greatest photosynthetic activity. Increasing light intensity, water, and carbon dioxide could also have an effect on the rate of photosynthesis.

________________ are reactants in the process of cell respiration.

• Water and carbon dioxide

• Water and oxygen

• Sugar and oxygen

• Water and sugar

Answer explanation

Sugar and oxygen are the reactants in the process of cell respiration and water and carbon dioxide are the products.

Water is one of the required reactants for photosynthesis. It provides electrons that are energized by sunlight and used to make energy carriers like ATP. Where do plants get the water they need for photosynthesis?

• Plants take in water from their leaves through the cuticle.

• Plants take in water from the air through their leaves.

• Plants take in water from the air through their stems.

• Plants take in water from the soil through their roots.

Answer explanation

The cuticle protects leaves from water loss. Water moves through the vascular tissue from the roots through the stem, to the leaves, where photosynthesis occurs.

Which of these products is formed during the metabolic reactions of cellular respiration?

• glucose

• water

• oxygen

• fructose

Answer explanation

In cellular respiration, glucose molecules are broken down to form ATP, the energy needed for a cell to function properly. During this process, glucose and oxygen are needed to make the ATP, and carbon dioxide and water are formed as waste products.