Biology Topic 6 Plant structures P2

What does photosynthesis occur in?

Plants and algae

What kind of reaction is photosynthesis?

Endothermic

What’s an endothermic reaction?

A reaction that takes in more energy than it releases

What is the equation for photosynthesis?

Carbon dioxide + water → glucose + oxygen

What is the chemical symbol for glucose?

C6H12O6

Where do plants do photosynthesis?

Chloroplasts

What is the rate of photosynthesis affected by?

Temperature

Light intensity

Carbon dioxide concentration

what is the effect of temperature?

• With an increase in temperature, the rate of photosynthesis increases

• as the reaction is controlled by enzymes, this trend continues up to a certain temperature until the enzymes begin to denature and the rate of the reaction decreases

What is the effect of light intensity?

For most plants, the higher the light intensity, the faster the rate of the reaction.

What is the effect of carbon dioxide concentration?

• carbon dioxide is needed to make glucose

• As the concentration of carbon dioxide increases, the rate of reaction increases.

What can temperature, light intensity and CO2 concentration become if they’re in short supply?

A limiting factor

What is a root hair cell specialised to do?

Take up water by osmosis and mineral ions by active transport from the soil as they are found in the tips of roots

What are the adaptations of root hair cells?

• large surface area meaning more water can move in

• Large permanent vacuole affects the speed of movement of water from the soil to the cell

• Mitochondria provide energy from respiration for the active transport of mineral ions into the root hair cell

What is the function of a xylem cell?

Transport water and mineral ions up the plant from the roots to the shoots

Adaptations of xylem cells

• upon formation a chemical called lignin is deposited which causes the cells to die ( we say the cells have become lignified) The cells become hollow and are joined end to end to form a continuous tube so water and mineral ions can move through

• Lignin is deposited in spirals which helps the cells withstand the pressure from the movement of water

Function of phloem cells?

Specialised to carry the products of photosynthesis (food) to all the parts of the plants

Adaptations of the phloem cells

• cell walls of each cell form structures called sieve plates when they’re break down, allowing the movement of substances form the cell to cell

• Unlike xylem the cells are alive

• Mitochondria of companion cells supplies cells with energy

• Energy is used to transport sucrose around the plant