Photosynthesis

Photosynthesis

We've got energy yes we do!

• All energy starts with SUNLIGHT!

• Plants are autotrophs, which means they make their own food and don't have to consume other organisms (hetertrophs can't make their own food)

• The process they use to make their own food is called PHOTOSYNTHESIS

Multiple Choice

Which phrase is an example of autotrophic nutrition?

• a cow eating grass in a field

• a mushroom digesting a dead log

• an apple tree making its own food

• a tapework feeding in the body of a dog

Multiple Choice

Why is a mushroom considered a heterotroph?

• It manufactures its own food

• It divides by mitosis

• It transforms light energy into chemical energy

• It obtains nutrients from its environment

Chemical Reactions

• In a chemical reaction, we start with the reactants which rearrange/transform into the products

• reactants ----> products

Photosynthesis Chemical Equation

• carbon dioxide + water ----> glucose + oxygen

• CO₂ + H₂O -------> C₆H₁₂O₆ + O₂

Multiple Select

What are the REACTANTS of photosynthesis?

• Carbon dioxide

• Sunlight

• Water

• Oxygen

• Glucose

Multiple Select

What are the PRODUCTS of photosynthesis?

• Oxygen

• Sunlight

• Carbon Dioxide

• Glucose

• Water

Multiple Choice

A group of students placed spinach leaves in a beaker of water in full sunlight. After several hours, small bubbles appeared on the leaves. These bubbles probably consisted of:

• H₂O

• O₂

• CO₂

• H₂

Multiple Choice

Which of the following processes allows the cells of an organism to use carbon from the environment?

• mitosis

• fertilization

• transpiration

• photosynthesis

Location

• Photosynthesis mainly occurs in the green leaves of a plant

• Leaves are covered with a waxy cuticle on top (wax is a lipid which means its hydroPHOBIC)

• The bottom of the leaves have openings called stomata (which is plural for stoma) which allows for the carbon dioxide to come in and the oxygen to exit

• The stoma is made of GUARD CELLS which let the openings close and open as needed

Multiple Choice

Leaves of green plants contain openings known as stomata, which are opened and closed by specialized cells allowing for gas exchange between the leaf and the outside environment. Which phrase best represents the net flow of gases involved in photosynthesis into and out of the leaf through these openings on a sunny day?

• carbon dioxide moves in; oxygen moves out

• carbon dioxide and oxygen move in; ozone moves out

• oxygen moves in; nitrogen moves out

• water and ozone move in; carbon dioxide moves out

CHLOROPLASTS!

• Cells inside the leaf have a bunch of chloroplasts

• There are two parts of a chloroplast photosynthesis takes place in: the granum, which is made of stacks of disk like thylakoids, and the stroma (don't get this confused with stoma)

Photosynthesis has two stages

The light dependent reaction which requires light, and the light independent reaction, which does not require light.

Light Dependent Reaction

• occurs in the thylakoid of the grana

• chlorophyll absorbs light which creates energy (ATP & NADPH) to use in the next step

• water molecules are split and oxygen is released

Multiple Choice

Which molecule in plant cells first captures the radiant energy from sunlight?

• glucose

• carbon dioxide

• chlorophyll

• adenosine triphosphate

Light Independent Reaction

• AKA the Calvin Cycle or carbon fixation

• occurs in the stroma of the chloroplast

• uses the NADPH & ATP from the light dependent reaction along with carbon dioxide to create glucose

The glucose created can be:

• converted to sucrose and carried to other parts of the plant. 

  
  

• converted into starch and stored. 

  
  

• converted to other organic molecules as needed.

Multiple Choice

Eating a sweet potato provides energy for human metabolic processes. The original source of this energy is the energy:

• in protein molecules stored within the potato

• from starch molecules absorbed by the potato plant

• made available by photosynthesis

• in vitamins and minerals found in the soil

Limiting factors:

• There are three factors that can limit the rate of photosynthesis: light level, carbon dioxide level, and temperature

Limiting factors:

There are three factors that can limit the rate of photosynthesis: light level, carbon dioxide level, and temperature

Open Ended

The reactions in photosynthesis require the use of enzymes. Why would a high temperature have an effect on the rate of photosynthesis?

Multiple Choice

Scientists have found that although plants require light to carry on photosynthesis, very high levels of sunlight can kill some plants. This illustrates that many biochemical processes may occur:

• more rapidly when temperatures are very high

• within a specific range of conditions

• best in the absence of abiotic factors

• even if homeostasis is disrupted

Multiple Choice

Which of these would lead to a lower rate of photosynthesis in a plant?

• an increase in the amount of oxygen in the air

• a decrease in the amount of oxygen in the air

• an increase in the amount of carbon dioxide in the air

• a decrease in the amount of carbon dioxide in the air