Photosynthesis and Respiration Chapter 11.1 Photosynthesis and Respiration

Movement of Materials in Plants Plants make their own food using water, carbon dioxide, and chemicals from the soil. Water is taken up through roots. Leaves are where gas exchange takes place – oxygen leaves the plant and carbon dioxide enters the plant. Water vapor also will leave the plant through leaves.

Leaf Structure and Function The outer layer of the leaf is the epidermis. A waxy cuticle covers the epidermis to help keep water in the leaf. The epidermis is also full of small openings called stomata that allow gas exchange. Guard cells surround the stomata and control whether it is opened or closed. Stomata will be open during the day and closed at night usually. Inside the leaf is also the spongy layer which is filled with carbon dioxide and water vapor and the palisade layer where many chlorophyll for making plant food are.

Chloroplasts and Plant Pigments Plants contain chloroplasts. This makes the plant green because they contain a green pigment called chlorophyll. Chlorophyll will absorb all other colors of light and reflect green, that is why a plant looks green. In fall the chlorophyll will break down and that is why the leaves change color. Chlorophyll is very important because it absorbs sunlight to make food.

The Food Making Process Photosynthesis – the process where a plant traps light energy and produces sugars. Photosynthesis only takes place in cells that have chloroplasts – mostly in the leaves. Chemical equation for photosynthesis: 6CO2 + 6H20  C6H12O6 + 6O2

Light-Dependent Reactions Certain reactions that happen during photosynthesis require light. During this reactions light is trapped and used to make energy to make carbohydrates. Also during these reactions water is split into oxygen and hydrogen. The oxygen leaves the plant and the hydrogen is used later on by the plant.

Light Independent Reactions These reactions do not require light. They use carbon dioxide and products produced in the light dependent reactions. This part actually makes the glucose or carbohydrates for the plants (the food).

Importance of Photosynthesis Photosynthesis produces food. It is also important because it removes carbon dioxide and gives oxygen to the atmosphere.

The Breakdown of Food Respiration – chemical reactions that break food molecules down and release energy. Both plants and animals perform respiration. The chemical equation for respiration is: C6H12O6 + 6O2  6CO2 + 6H2O + energy

Aerobic Respiration Aerobic respiration means that it needs oxygen to take place. Before aerobic respiration can take place glucose has to be broken down in the cytoplasm.

Importance of Respiration Respiration changes the energy stored in food into usable energy for plants and animals.

Comparison of Photosynthesis and Respiration Photosynthesis store energy in food, while respiration breaks that down to release energy. Photosynthesis uses water and carbon dioxide as raw materials, while respiration uses glucose and oxygen. Photosynthesis produces glucose and oxygen while respiration releases water and carbon dioxide. Lastly photosynthesis takes place in chlorophyll while respiration takes place in the mitochondria.