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Chapter 11. Section 1. Taking in Raw Materials. To grow you need: Food Oxygen Used to release energy from food that you eat Carbon dioxide and water are produced as wastes that are removed when we exhale What does a plant need to grow?. Plants Need Food Too.
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Chapter 11 Section 1
Taking in Raw Materials • To grow you need: • Food • Oxygen • Used to release energy from food that you eat • Carbon dioxide and water are produced as wastes that are removed when we exhale • What does a plant need to grow?
Movement of Materials in Plants • Plants make their own food using water, carbon dioxide, and inorganic chemicals in the soil • They produce wastes when they make food
Movement of Materials in Plants • Most water is taken in through the roots • Leaves are where gas exchange occurs • Most water taken in leaves through the plant leaves • Carbon dioxide, oxygen, and water vapor enter and exit through the openings in the leaves
Leaf Structure and Function • Outer cell layer is the epidermis • Cuticle prevents the leaf from drying out • Sunlight reaches cells inside the leaf through the epidermis • Contains stomata • Guard cells open and close
Leaf Structure and Function • Stomata • More than 90% of water plants take in is lost through the stomata • Usually open during the day to take in raw materials to make food • Close during the day if too much water is being lost • Guard Cells • As water moves into the guard cells they swell and bend causing the stomata to open • As water is lost they deflate and close the stomata
Leaf Structure and Function • Spongy cell layer • Has open spaces • Carbon dioxide and water vapor fill in the empty spaces • Palisade cell layer • Chloroplasts have chlorophyll here • Most of the food is made here
Chloroplasts and Plant Pigments • Chloroplasts are green because they contain the green pigment chlorophyll • Leaves are green because the color green is reflected • The other colors of the visible spectrum are absorbed by the chlorophyll • In the fall some chlorophyll breaks down and other colors are visible
Food-Making Process • Photosynthesis: • Process in which chlorophyll traps light energy and sugar is produced • Only occurs in cells with chloroplasts
Light-Dependent Reactions • Light-Dependent Reactions need light to occur • Chlorophyll traps light • Light causes water to split into oxygen and hydrogen • Oxygen leaves the plant • Hydrogen is used in the reactions that don’t require light
Light-Independent Reactions • Light-Independent Reactions do not require light • Carbon dioxide is used • Light that was trapped earlier combines with carbon dioxide to make sugar • 1 important sugar made is glucose
Light-Independent Reactions • Glucose is the main source of food for plants • Excess is stored as other sugars and starches in the plant • When you eat carrots, beets, potatoes, or onions you are eating stored sugar and starches
Importance of Photosynthesis • 1: Produces food • 2: Release Oxygen and take in carbon dioxide
Breakdown of Food • Cellular respiration: • Series of chemical reactions that breaks down food molecules and releases energy
Cellular Respiration • 1st: Sugar molecules are broken down • 2nd: Smaller molecules enter mitochondria • 3rd: Oxygen breaks down the molecules into water and carbon dioxide • Releases energy
Importance of Cellular Respiration • Food contains energy but not in a form most cells can use • Cellular respiration allows food to change into an energy form all cells can use • Plants use the energy to transport sugar and to open and close the stomata
Comparing Photosynthesis and Cellular Respiration • Photosynthesis: • Combines carbon dioxide and water by using light energy • End products are glucose and oxygen • Energy is stored in food • Occurs only in cells that have chlorophyll
Comparing Photosynthesis and Cellular Respiration • Cellular Respiration: • Combines oxygen and food • Releases the energy in chemical bonds in food • End products are energy, carbon dioxide, and water • Has to have a mitochondria