How do sunflowers track sunlight?

Answer 1

Sunflowers track the sun through changes in turgor pressure. Potassium ions get pumped into the underside of the flower on its shady side (the side where the cells aren't sensing as much blue light), which increases the turgor pressure, which causes the nearby motor cells to get longer and bend. As the sun moves across the sky, the pressure changes so that the head of the flower follows the sun. At night, when there isn't any sun, the pressure subsides, the motor cells go back to their normal size, and the flowers just kinda do whatever until the next morning. A plant's movement in response to light is called phototropism in general, but this kind of movement in particular is called heliotropism--it's diurnal, quicker, and reversible, as opposed to phototropism, which is...not.

Answer 2

Sunflower like other flowering plants have special pigments in their leaves named chlorophylls. As the sun rays hit the surface of the leaves, chorophyll pigments become active. The sunlight or energy travels inside the leave due to electron gradient force which in turns activate several photosythetic centers. In some cases the energy or sunlight trapped in these center is used to make sugar carbon compounds that are exported to other part of the organism for reproduction, storage, and growth.

Answer 3

1
SUNFLOWER
Leaves gather sunlight
Sunlight provides energy for plants which they use in making food by photosynthesis
WHAT TO DO
Raise the leaf towards a source of light.
Q: What effect does this have on the meter?
(A: The highest reading on the meter shows
the best position for the leaf to receive
light.)
Q: How is this like real plants?
(A: Green plants have a pigment called
chlorophyll which absorbs light energy
which they use to make food by
photosynthesis.)
Place your hand over the leaf and shade it from
the light.
Q: What effect does this have on the meter?
(A: Covering the leaf stops the light being
collected and this is shown by a low reading
on the meter.)
Hold one of the panels above the leaf.
Q: What effect does this have on the readings?
(A: The reading will go down showing that
less light is getting to the solar cells.)
Q: How does this relate to the real world?
(A: When the Sun is obscured by clouds or
haze less light gets to leaves and less food
can be made.)
OTHER THINGS TO DO
Look at green plants in a wood. Which ones do
you think will get the most light? Higher leaves
get the most, so trees will always win. Land with
sufficient water and minerals, left to itself will
become forest.
DESCRIPTION
A model plant with solar panels simulates a plant’s
ability to collect light. The leaves can be raised
and lowered on the stem. The success of the
position is measured on the meter in the flower
face.
Two panels, one translucent and the other tinted,
can be held above the leaf simulating the effect
of cloud or haze.

2
FURTHER INFORMATION
Photosynthesis
Embedded in the leaves of this model are solar cells that pick up light and convert it into electrical
energy which is registered on the meter. This is analogous to the process by which green plants take
up energy from light. Plants use it to manufacture sugars. This process is called photosynthesis.
Chlorophyll
Green plants contain a substance called chlorophyll which absorbs the red and blue parts of the
spectrum of white light; it reflects the green part. It is the substance which uses the light energy to
manufacture the sugar glucose out of carbon dioxide from the air and water from the soil; oxygen is
the by-product.
Carbon dioxide + water + glucose + oxygen
Photosynthesis takes place in the chloroplasts of cell leaves. Plants arrange their leaves to get the most
sunlight. This is called phyllotaxis. Height is the best way of maximising light uptake. Thus trees will
dominate in any landscape where there is suitable soil and man has not cleared them. Any land with
sufficient essential materials and not cultivated by man will tend to climax forest.
Food chains
At the base of every food chain lies the process of food synthesis by plants. In the vast majority of cases
this is photosynthesis by green plants creating sugar, and from this other foods. Herbivores live off green
plants and carnivores off them. The Sun is the source of all our power. This is true of power from fossil
fuels – the product of photosynthesis in ages past. (The Sun also provides the energy for wind and water
power. Nuclear reactions in star like the Sun produce the elements for atomic power too.)
Organised by:
www.science.edu.sg/dsr

Answer 4

Its not just sunflowers though. Other plants grow toward sunlight!

Answer 5

A process called solartropism. Almost all plants will follow the sun on it's path (or our's around it, as the case may be).
Geotropism is the process by which roots grow downward. Likely uses gravity as a driving force, as opposed to light. I haven't seen the results of zero-gravity tests on plants that have been done to prove or disprove.

Answer 6

The scientists say that sunflowers have a cgps (Chlorophyll global positioning system) which tells them where they are at all times.
The only confusing times for these flowers is at dusk and dawn at
which time their calibration routine kicks in.

Answer 7

That is a great question.

Though plants do not contain identifiable eyes like animals, they do include fungus-like cells (Fungi are not plants. Plants, animals, bacteria, and fungi are different kingdoms of life) which contain light-sensitive pigments. These cells control growth of fungus spores to grow in the direction of maximum light.

Answer 8

lowflyer1 is right in some regards. Its called gravatropism. The plant uses auxin to figure out where the light is.

Answer 9

hello thats why it is called SUNflower(lol)

Answer 10

they have light sensors

(no... that wasnt a silly answer)