Grade 10 Biology: Lesson 9

Active transport

________ moves the Auxin into the cells of the shaded side of the plant.

Animals

________ have the ability to sense and then respond to their environment by thinking and acting.

Phototropism

________ allows the plant to maximize the amount of light that is absorbed by the leaves which in turn maximizes the amount of Photosynthesis within the leaves.

Charles Darwin

In 1880 ________ and his son Francis performed experiment to prove that plants will grow toward a light source.

Negative Gravitropism

________ occurs in the Stems of plants in which the stem will grow upwards against gravity.

Positive Gravitropism

________ occurs in the Roots of plants which the roots will grow downwards with gravity.

Gravitropism

________ is a plant growth response to Gravity (an environmental stimulus)

Auxins

Plant Growth Chemicals

Plant tip Partially covered by chemical soaked Agar

Plant Grew Away from the Side with the Chemical Soaked Agar

what are plant responses to environment called

responses to the environment are called Tropisms in plants

_______ cannot think, however, they do Respond to their environment as well

Plants cannot think, however, they do Respond to their environment as well

what is phototropism?

The growth of a plant toward a light source

how is phototropism done?

- to bend towards light, plant will have cells of stem grow at different rates
- Cells on side of the stem that further from light will grow longer than cells on side of stem closer to the light

what happens to the cells further from light in phototropism?

Cells on the side of the stem that is further from the light will grow longer than the cells on the side of the stem that are closer to the light

what was the purpose of Darwin's experiment in 1880?

to prove that plants will grow toward a light source

outcome of darwins experiment?

not only proved that plants respond to light source, they also proved that it was the tip of the plant that would sense, respond and then send signals to rest of the plant based on the light it received

what part of the plant sends signals to the rest of the plant based on the light it receives?

the tip of the plant

what was the purpose of the Boysen Jensen experiment ?

to learn more about the actual signal (from Darwin's experiment) that was sent from the tip of the plant in response to light

what was the outcome of the Boysen Jensen experiment?

- signal could not diffuse through the Mica ( but did through the gelatin)
- plant grew straight up and did not respond to light, proving that signals are sent from tip of plant to the rest of it

what was the purpose of fritz went's experiment?

to determine if a growth chemical signal is produced in the plant tips and is sent to the rest of the plant

what was the outcome of fritz's experiment?

found that the plants grew in different ways and concluded that the chemical produced in the plant tips stimulated Growth

Plant tip ___________ covered by chemical soaked Agar = Plant Grew Straight Up

Plant tip Completely covered by chemical soaked Agar = Plant Grew Straight Up

Plant tip Completely covered by ___ - ________ soaked Agar - Plant Did Not Grow At All

Plant tip Completely covered by Non-chemical soaked Agar - Plant Did Not Grow At All

auxin means (in Greek)?

to grow

what are auxins?

growth chemicals that are produced in the tip of the plant as it responds to a light source

what causes the cells on the shaded side of the cell to grow longer?

Auxins

what's nastic response?

response to Touch
(ex: Venus fly trap and mimosa plant)

____________ also relies on the ability of the plant signal Auxin to elongate the cells on one side of the stem or the roots

Gravitropism also relies on the ability of the plant signal Auxin to elongate the cells on one side of the stem or the roots

how does gravitropism work in the stem?

- respond to gravity by releasing Auxin from its tip
- Auxin sent to lower side of stem stimulating the cells on that side of the stem to elongate
- stem will bend to grow upwards against gravity

how does gravitropism work in the roots?

- Auxin sent to lower side of roots preventing cells on that side of the root from elongating
- roots will bend to grow downwards with gravity