Plant Processes Chapter 12

Fertilization Pollen is transported from the anther to the stigma and a tube forms. Pollen goes down tube (style) to ovule Sperm cell fuses with egg cell. The egg develops into a seed. http://www.youtube.com/watch?v=RuYrFwDuYn0&feature=related

Familiar Fruits Fruits form in the ovary of the flower as the ovules are developing into seeds. The fruit holds and protects the seeds. http://www.youtube.com/watch?v=bwCpQflmQG4

Seeds become new plants Seeds can become dormant after the young plant inside the seed stops growing. When a seed is planted in an environment that has water, oxygen and the right temperature, it sprouts. http://www.youtube.com/watch?v=rDN0yAFcQok

Other methods of reproduction Many flowering plants can reproduce asexually (without flowers, seeds, or fruits.) In asexual reproduction, part of the plant produces a new plant. http://www.youtube.com/watch?v=drcnTg7ZCoc

What happens during photosynthesis? During photosynthesis plants take in carbon dioxide and water and absorb light energy. They make sugar and release oxygen. http://www.youtube.com/watch?v=LgYPeeABoUs

Chlorophyll Chlorophyll is a green pigment that is in the chloroplasts of plant cells. Chlorophyll reflects green light, which is why plants appear green.

Gas Exchange- plant breathing Plants take in CO2 through little holes in the cuticle called stomata (one is called stoma) Transpiration is the release of water (like sweating). http://www.youtube.com/watch?v=U4rzLhz4HHk

Plant Tropisms Growth in response to stimulus is called tropism. Plant growth toward a stimulus is positive tropism, plant growth away from a stimulus is negative tropism. http://www.youtube.com/watch?v=I7TmX0rrNRM http://www.youtube.com/watch?v=zctM_TWg5Ik

Phototropism A change in the growth of a plant in the direction of light is called phototropism. The bending occurs because cells in one side of the shoot grow faster than on the other side of the shoot. http://www.youtube.com/watch?v=Ze8NV7cvW8k&feature=related

gravitropism Roots will naturally grow in the direction of gravity, and shoots will naturally grow in the opposite direction of gravity. http://www.youtube.com/watch?v=cXc6AVVa2_E http://www.youtube.com/watch?v=mYZXax8V_L0&feature=fvst

Seasonal Responses The difference between day length and night length is an important stimulus for many plants. Some plants flower only in late summer and early autumn when the night is long. These are called short-day plants. Others flower when the night is short. These are called long-day plants. Examples of short day plants: poinsettias, ragweek, chrysanthemums Long-day plants: clover, spinach, lettuce

Seasonal Changes in Leaves All trees lose their leaves at some time. Evergreens shed and grow leaves all year. Deciduous trees lose all their leaves at the same time each year, usually before winter. Having bare branches reduces the loss of water through transpiration. In tropical areas with wet and dry seasons, deciduous trees shed leaves before the dry season. Leaves often change color due to a break down in the chlorphyll that normally made the leaves green. When chlorophyll is lost, the other pigments of the leaves are revealed.

Plant Growth Chapter 12, section 4

Heredity A plants traits, like leaf shape or red flowers, are determined mainly by DNA.

Environment A plant’s traits are determined by genes, but its behavior and appearance can be affected by the environment.

Plant Hormones Heredity and environment can affect a plant’s production of Hormones. Hormones are chemical messengers that carry information from one part of an organism to another. Hormones are produced in small ammounts but have a strong effect on the organism. A plant hormone is produced in a specific part of the plant, such as the shoot tips.

Auxin Auxin is one of five major plant hormones. It is produced in shoot tips and has many effects on plant growth. For example, Auxin is involved in phototropism. When a plant is exposed to light from one direction, auxin travels from the shoot tip to the shaded side of the stem. It causes the cells on that side of the stem to grow longer. As a result, the stem will bend in the direction of the light.

Gibberellin Gibberellin affects plant growth in many ways. It causes plants to grow tall, and flower stalks to grow long. Farmers often apply plant hormones to plants to make them grow in desirable ways.