Practise Questions 2

• What is the role of the nucleus?

  Contains the genetic information (DNA) of the cell
• What is the role of the cell membrane?

  Controls what enters and leaves the cell
• What is the role of the chloroplast?

  Photosynthesis
• What is the role of the cellulose cell wall?

  Keeps the cell strong and rigid
• How are muscle cells adapted to their job of contracting?

  Many mitochondria release energy through respiration
• What are the reactants for photosynthesis?

  Carbon dioxide

  Water
• What are the products of photosynthesis?

  Glucose

  Oxygen
• What is the chemical formula for glucose?

  $C_6H_{12}O_6$
• What is glucose stored in animal cells as?

  Glycerol
• What is glucose stored in plant cells as?

  Starch
• What are the limiting factors for photosynthesis?

  Light intensity, carbon dioxide concentration, temperature and amount of chlorophyll.
• Where in a plant is chlorophyll found?

  Chloroplasts
• How do you measure the rate of photosynthesis in pond weed?

  Volume of oxygen produced per minute

  (Counting oxygen bubbles produced in a set period of time)
• What are the control variables when you are investigating the effect of light intensity on the rate of photosynthesis (make your

  results valid).

  Temperature (place test tube in a water bath)

  Carbon dioxide concentration

  Surface area of leaves
• How do you change the light intensity?

  Distance of the lamp from the pondweed
• Which organ allows the entry of water into a plant?

  Root
• By which process does water enter the root hair cells?

  Osmosis
• By which process do mineral ions enter a plant?

  Active transport
• How does water move from the roots to the leaves? 

  Through the xylem
• What is the function of the stomata on a leaf? 

  Allows carbon dioxide to diffuse in and water vapor to diffuse out
• Which cells control the opening and closing of the stomata?

  Guard cells
• What is translocation?

  The movement of dissolved sugars through the phloem of a plant
• Give one use of sugars in living things such as plants?

  Respiration