Q: Which equation best represents the process of photosynthesis that leads to starch production in leaves?

$$6 \text{CO}_2 + 6 \text{H}_2\text{O} \xrightarrow{light} \text{C}_6\text{H}_{12}\text{O}_6 + 6 \text{O}_2$$

Question 1

A pigment solution absorbs light at various wavelengths. If the absorption spectrum shows the lowest absorption in the green region and the highest absorption in the red and blue regions, what color would the solution most likely appear to the human eye?

Accepted Answer

Green

Question 2

During paper chromatography of plant pigments, why does the pigment that travels the farthest up the paper move faster than the others?

Accepted Answer

It is more soluble in the solvent and less attracted to the paper.

Question 3

A plant is kept in a greenhouse with light 24 hours a day. After boiling a leaf in ethanol, placing it in water, and then in iodine, what result would you expect and why?

Accepted Answer

The leaf turns blue-black due to starch presence, indicating photosynthesis occurred.

Question 4

A plant is kept in darkness for a week. After treating a leaf with ethanol, water, and iodine, what result would you expect and why?

Accepted Answer

The leaf remains brown or yellow because no starch is present.

Question 5

If a plant is illuminated for 6 hours and kept in darkness for 18 hours, and a leaf is tested with iodine 10 hours into the dark cycle, what is the most likely outcome?

Accepted Answer

The leaf remains brown/yellow, indicating starch has been used up during darkness.

Question 6

Which of the following best explains why a pigment appears green to the human eye?

Accepted Answer

It reflects green light and absorbs red and blue light.

Question 7

In chromatography, what property of a pigment determines how far it travels up the chromatography paper?

Accepted Answer

Its solubility in the solvent

Question 8

Which equation best represents the process of photosynthesis that leads to starch production in leaves?

Accepted Answer

$$6 	ext{CO}_2 + 6 	ext{H}_2	ext{O} \xrightarrow{light} 	ext{C}_6	ext{H}_{12}	ext{O}_6 + 6 	ext{O}_2$$

Question 9

Why is ethanol used in the process of testing leaves for starch after photosynthesis experiments?

Accepted Answer

To remove chlorophyll, making color changes more visible

Question 10

A student observes that after performing chromatography on a leaf extract, one pigment travels almost to the top of the paper while others remain near the bottom. What can be inferred about the pigment at the top?

Accepted Answer

It is more soluble in the solvent and less attracted to the paper.

Question 11

If a pigment absorbs most strongly at 450 nm (blue light) and 680 nm (red light), which color of light is least absorbed?

Accepted Answer

Green

Question 12

Which of the following best describes the role of iodine in the starch test for leaves?

Accepted Answer

Iodine reacts with starch to produce a blue-black color.

Question 13

A plant is kept in continuous darkness. Which of the following best explains why its leaves do not turn blue-black when tested with iodine?

Accepted Answer

Photosynthesis does not occur, so starch is not produced.

Question 14

Which of the following statements about pigment absorption spectra is correct?

Accepted Answer

A pigment appears the color of light it absorbs least.

Question 15

If a plant is exposed to light for only 6 hours a day, what happens to the starch content in its leaves during the 18 hours of darkness?

Accepted Answer

Starch content decreases as it is used for respiration.

Study Guide: Pigments, Light Absorption, and Photosynthesis Experiments

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