Photosynthesis Section 4.1

Photosynthesis- the process where a cell captures the energy in sunlight and uses it to make food like glucose.

Living things obtain energy directly from sunlight (plants in photosynthesis) or indirectly (animals when they eat plants).

B. An organism that makes its own food is called an autotroph

An organism that can’t make its own food and must eat other organisms to obtain energy is called a heterotroph.

Photosynthesis Equation sunlight 6CO2 + 6 H2O  C6H12O6 + 6O2 (Reactants) (Products) Carbon dioxide + water + sunlight yields glucose + oxygen

Two stages of Photosynthesis

Stage 1: Capturing the Sun’s Energy 1. Chloroplasts in leaf plant cells contain an energy absorbing pigment called chlorophyll 2. Chlorophyll captures light energy and converts it to a usable energy form 3. This energy is used to power stage 2

Stage 2: Using energy to make food… Water is taken in from the soil, up the stem and delivered into the leaf cells.

2. Carbon dioxide enters the under surface of the leaf through openings called stomata.

3. In the leaf the water and carbon dioxide go through a series of chemical reactions and produce sugar in the form of glucose.

4. They also produce oxygen gas (O2) which is released to the air 4. They also produce oxygen gas (O2) which is released to the air. (we can then breathe it in).

5. Energy made in stage 1 powers this chemical chain of reactions.

F. Equation: 6CO2 + 6 H2O  C6H12O6 + 6O2 (Reactants) (Products)

The equation tells you that: *6 molecules of carbon dioxide gas + *6 molecules of water *In the presence of light Make *1 molecule of glucose sugar and *6 molecules of water…

Glucose goes into the mitochondria… and the process of respiration begins… Next topic Cellular Respiration.

Let’s see what you know… What cell in the leaf undergoes photosynthesis? What organelle? What types of living things can make energy directly from sunlight? The name of the energy absorbing pigment in the cell’s chloroplast is __________.

What three ingredients (reactants) enter the plant to be used in photosynthesis? What are the two products? Where does the plant obtain the energy needed to power stage 2 of photosynthesis?

Assessment 4.1 1a. Why do living things need energy? *All living things are made of cells which require energy to carry out their functions. 1b. How do plants obtain energy? * Plants trap energy from the sun and convert it to sugar which they then can break down to make cell energy.

*The leaf has stored energy in it from photosynthesis. 1c. An insect eats a leaf. Explain how the insect depends on the sun for energy. *The leaf has stored energy in it from photosynthesis. 2a. What chemical equation sums up the events of photosynthesis? *6CO2 + 6 H2O  C6H12O6 + 6O2

2b. What are the substances needed for photosynthesis 2b. What are the substances needed for photosynthesis? *Carbon dioxide and water What substances are produced during photosynthesis? *Glucose and oxygen

2c. Would you expect a plant to produce more oxygen on a cloudy day or a sunny day? Explain. * Sunny day since more light is available for photosynthesis.