PLANT HORMONES

A type of plant will grow tendrils and wind round a support. Name this type of reaction.

• Tropism.

• Nastic response.

• Reflex action.

• Taxis response.

What is the role of auxin that causes a plant to bend towards light?

• The concentration of auxin in the plant increases when there is light.

• Auxin causes uniform growth on every stem.

• Auxin causes cells that are on the dark side to grow faster.

• Auxin causes the increase in the number of plant cells.

Tags

NGSS.MS-LS1-5

The growth hormone that is used to speed up the ripening of fruits for export is

• giberellin.

• ethylene.

• cytokinin.

• auxin.

What is the reaction that is shown by the plant in the figure above?

• Positive hydrotropism.

• Negative phototropism.

• Positive thigmotropism.

• Negative geotropism.

The figure above shows a mimosa plant. What is the conclusion that can be derived based on the reaction in the figure.

• The mimosa plant shows a seismonastic reaction.

• The leaf of the mimosa becomes sturgid when touched.

• The osmotic pressure in the mimosa cell increases when touched.

• The temperature of the glass rod becomes very high until the leaf fades when touched.

The figure above shows the reaction of a plants to a stimulus. What is the reaction shown by the plants?

• Thermonasty.

• Thigmonasty.

• Photonasty.

• Seismonasty.

The movement of Euglena sp and Volvox sp. towards moderate light itensity is a type of reaction to an external stimulus. What is the reaction?

• Photonasty.

• Phototaxis.

• Thermonasty.

• Phototropism.

The figure above shows four coleoptiles P, Q, R and S that are exposed to unilateral light. After two days, which coleoptile will move towards the light?

• P only.

• R only.

• P and R only.

• P, Q and S only.

Tags

NGSS.MS-LS1-5

The figure above shows an experiment

that is done on two plants of the same species. Both plants are left in the open.

What will happen to the two plants after two weeks

I Plant B bends towards the opening of

the box.

II The auxin in stem A is distributed

uniformly.

III The auxin in stem B is not distributed

uniformly.

IV Plant A bends to the right.

• I, II and III only.

• I, II and IV only.

• I, III and IV only.

• II, III and IV only.

Tags

NGSS.MS-LS1-5

The figure below above shows an experiment to study the effect of auxin towards the growth of the coleoptiles. Which of the following conclusions are true about the experiment?

I Auxin is produced at the tip of the

coleoptiles and diffuses to the bottom to stimulate

growth.

II The supply of auxin is cut off in the

dark.

III Auxin cannot penetrate a mica plate.

IV Auxin can diffuse through a block of

agar-agar.

• I, II and III only.

• I, III and IV only.

• II, III and IV only.

• I, II, III and IV.

Tags

NGSS.MS-LS1-5