Hormones and the Control of Plant Growth Plants

Hormones and the Control of Plant Growth - Plants respond to changes to their environment

Can you remember the 7 life processes? Movement Respiration Sensitivity Nutrition Excretion Reproduction Growth

• In what ways are plants sensitive to their surroundings? • Why is this important?

PLANTS ARE SENSITIVE • Plants respond to their surroundings • GEOTROPISM – response to gravity • HYDROTROPISM – response to water • PHOTOTROPISM – response to light • Tropisms are controlled by hormones known as Auxins • Growth of plants occur from the tips of the roots and shoots

PLANT ROOTS • Roots always grow DOWN (positively geotropic) • Roots grow towards WATER (positively hydrotropic) • So that they can anchor the plant and absorb minerals/water • Roots grow away from LIGHT (negatively phototropic)

PLANT SHOOTS • Shoots grow UP (negatively geotropic) • Shoots grow towards light (positively phototropic) • So that they can absorb light for photosynthesis

Germinating seeds What can you determine from the photos?

• Tropisms – Britannica • Time lapse germination • Negative geotropism • Phototropism

AUXIN • Auxin affects how plants grow. It’s a growth hormone. A response happens due to an uneven distribution of the hormone

Auxin moves to the shaded side of the shoot and causes the cells there to elongate. This results in the shoot bending towards the light.

Describe and explain the growth of each plant

1. Why are the responses of shoots and roots so important in the life of plants?

YOU SAY WE PAY

Growth

Tropism

Germinate

Light

Shoot

Negative

Hydrotropic

Root

Down

Gravity

Photosynthesis

Geotropic

Hormone

Sensitivity

Positive

Water

Phototropic

Auxin

Up

Tips

Plant