Chapter 13

13.1: photosynthesis13.2 reproduction of flowering plants

Warm up

•Where do you get the energy you need to stay alive???????????

Objectives • Define photosynthesis.• Describe the structure of the chloroplast.• Explain how do plants make sugar.• Explain how do plants use energy from sugar.• Use chemical equations to describe photosynthesis and cellular

respiration.• Compare between photosynthesis and cellular respiration.• Describe how gas is exchanged in the leaves of plants.• List two benefits of photosynthesis.• Distinguish between pollination and fertilization.• Recognize the different parts of a flower.• Explain how seeds and fruits are produced.

Introduction

• Plants don’t have lungs. But like you, plants need air. Air contains oxygen, carbon dioxide, and other gases. Your body needs oxygen, and plants need oxygen. But what other gas is important to plants?

Photosynthesis

• Photosynthesis is possible because of …(Chloroplast)

• Grana contains green pigment called …• Chlorophyll absorbs many wavelengths of light but

it reflects more green wavelengths than other color. That’s why plants look green.

Making sugar and using energy

• The light energy captured by chlorophyll is used to make sugar molecule, according to the following chemical reaction:

6H20 + 6CO2 C6H12O6 + 6O2

Sugar molecules contain energy, plant cells use this energy to carry different life processes.

Light energy

Making sugar and using energy

• Plant cells break down sugar molecules in order to release energy in a process called cellular respiration.

• Let’s write down the chemical equation of cellular respiration.

C6H12O6 + 6 O2 6 CO2 + 6 H20Where does the excess glucose go?It is stored in the form of sucrose or starch.

• Fill in the table by comparing between cellular respiration and photosynthesis:

Photosynthesis Cellular respiration

Substances needed Carbon dioxideWaterLight energy

Glucose Oxygen gas

Products Glucose Oxygen gas

Water Carbon dioxide

Gas exchange• Many above-ground plant surfaces are covered by

a waxy cuticle.• Cuticle protects the plant from water loss.• How does a plant get CO2 through this barrier?

Importance of photosynthesis

• Organisms rely on plants in order to get the energy they need. (plants store light energy as chemical energy)

• All organisms depend on cellular respiration for the production of energy. The oxygen needed is provided by photosynthesis

Reproduction of flowering plants

• Difference between pollination and fertilization.• what are the different parts of the

flower.• How are seeds formed.