Lesson Worksheet: Plant Hormones Biology

Start Practising

In this worksheet, we will practice outlining the roles of different plant hormones and describing simple experiments to investigate them.

Q1:

In Boysen-Jensen’s experiment, the decapitated coleoptile restored its ability to bend towards the unidirectional light when the cut tip was fixed again onto the coleoptile using gelatine. On which side of the coleoptile tip did the auxins accumulate?

AAuxins accumulated on the shaded side, which stimulated cells’ growth on this side and resulted in the bending of the coleoptile towards the light.
BAuxins accumulated on the illuminated side, which inhibited cells’ growth on this side and resulted in the bending of the coleoptile towards the light.
CAuxins accumulated on the illuminated side, which stimulated cells’ growth on the shaded side and resulted in the bending of the coleoptile towards the light.
DAuxins accumulated on the shaded side, which stimulated cells’ growth on the illuminated side and resulted in the bending of the coleoptile towards the light.

Q2:

Frits Went is a biologist who carried out an experiment on oat coleoptiles to demonstrate the presence of plant growth hormones (auxins) in the tip of the seedlings. In the following figure, an agar block is placed on one side of a decapitated coleoptile which is placed in a dark room.

Based on Went’s observations, if the agar block contains auxins, .

Athe side of the stem on which the agar block is placed will grow slower than the opposite side due to the absence of light
Bthe auxins will distribute equally on both sides due to the absence of light, causing the stem to grow up straight
Cthe stem will bend away from the side on which the agar block is placed
Dthe stem will bend towards the side on which the agar block is placed

Q3:

In light of your study of auxins, which of the following would most likely be their main commercial use in agriculture?

AInhibiting the growth of roots so that crops would need a smaller amount of water
BProtecting the crops from birds and pest insects due to their toxic effect
CStimulating the vertical growth and the development of different parts of the plant
DDirecting the growth of the shoots of crop plants towards the sunlight to track the direction of the Sun

Q4:

The provided diagram shows a coleoptile undergoing light tropism.

If we took a tissue sample from side A and side B to quantify the concentration of auxins in each side, what should we expect to find?

AThe samples from both sides will have equal levels of auxins.
BThe samples from both sides will have no auxins at all.
CThe sample from side A will have more auxins than that from side B.
DThe sample from side A will have less auxins than that from side B.

Q5:

During phototropism, auxins are produced .

Ain the illuminated side and diffuse to the shaded side of the stem
Bin the stem tip and accumulate on the shaded side
Cin the shaded side of the stem
Donly in the roots and diffuse to the stem

Q6:

A plant seedling was put in a cupboard and a single light bulb was hung above it for 2 days. The concentration of auxins of the coleoptile tip would be

Ahigher on the right side
Bhigher on the illuminated side
Chigher on the left side
Dequal on both the right and left sides

Q7:

A potted plant was left horizontally on its side for a few hours. A sample, A, was taken from the lower side of the stem tip to measure the concentration of auxins. After several days, another sample, B, was taken from the same area from which sample A was taken from the stem tip. Which of the following correctly compares the auxin concentrations in the two samples?

AThe auxin concentration is the same in samples A and B, and it is low in both.
BThe auxin concentration is the same in samples A and B, and it is high in both.
CThe auxin concentration is larger in sample B than in sample A.
DThe auxin concentration is larger in sample A than in sample B.

Q8:

In high concentrations, what effect do auxins have on cells in the root?