PLANT PROCESSES

ENERGY PROCESSING IN PLANTS

Materials For Plant Processes

• To survive, plants need food, water, and oxygen.

• Roots absorb water which travels inside xylem cells to all parts of a plant.

• Most plants make their own food (Glucose) which flows to all plant cells.

• Plants require oxygen and carbon dioxide to make food.

PHOTOSYNTHESIS

• Photosynthesis is a series of chemical reactions that converts light energy into chemical energy (Glucose)

PHOTOSYNTHESIS• Leaves are the major- food producing organs of plants.

• The cells that make up the top layer of a leaf are flat, irregularly shaped cells called epidermal cells.

• On the bottom of the epidermal layer of leaves are small openings called stomata.

PHOTOSYNTHESIS• Mesophyll cells contain chloroplasts, the organelle where

photosynthesis occurs.

• Chemicals that can absorb and reflect light are called pigments.

• The pigment chlorophyll reflects green light, absorbs other colors of light, and uses this energy for photosynthesis.

PHOTOSYNTHESIS

• During photosynthesis, water molecules are split apart releasing oxygen into the atmosphere.

• Sugars are made in the second step of photosynthesis.

• Photosynthesis is important because it produces most of the oxygen in the atmosphere

CELLULAR RESPIRATION

Cellular Respiration – converts the energy in food molecules into a usable form of energy called ATP

CELLULAR RESPIRATION

• Occurs in the mitochondria of Eukaryotic cells and requires oxygen

• Glucose broken down

• Large amounts of usable energy called ATP are produced

• Water and Carbon Dioxide is given off

CELLULAR RESPIRATION

• Cellular respiration is important to plants because without it they could not grow, reproduce, or repair tissue

• Life on Earth depends on a balance of photosynthesis and cellular respiration

Plant Responses

Stimuli are any changes in the environment that cause an organism to react.

Plants respond to different environmental stimuli such as:

lighttouchgravity

A tropism is a response that results in plant growth toward or away from a stimulus.

Phototropism Tendency of plants to grow toward a source of

light

• Leaves and stems tend to grow in the direction of light

• Roots grow away from light

Thigmotropism A response of a plant to touch

Gravitropism

Response of a plant to the force of gravity Stems grow away from gravity Roots grow toward gravity

Photoperiodism Response to the number of hours of

darkness in its environment.

Long-day plants- flower when exposed to less than 10-12 hours of darkness

Short-day plants- require 12 or more hours of darkness for flowering to begin

Day-neutral plants- flower when they reach maturity and the environmental conditions are right.

Hormone Substances that act as chemical

messengers. They are produced in one part of an

organism and affects another part of the same organism

Auxin Hormone that caused increased plant

growth.

Ethylene Plant hormone that stimulates fruits to

ripen

Gibberellin

Hormone that increases the rate of cell division and cell elongation in stems and leaves and fruit.

Cytokinin Plant hormone that increases the rate of cell

division in some plants and slow the aging process of flowers and fruits

Causes dormant seeds to sprout