Cell structure and transport

• How many pairs of chromosomes do humans have?

  23 pairs of chromosomes
• What is the purpose of the cell cycle?

  The cell cycle makes more cells.
• What are stem cells?

  Stem cells are undifferentiated cells.
• What can stem cells develop into?

  Specialized cells
• Where are plant stem cells found?

  In the meristem tissues of plants
• How can plant stem cells be used in agriculture?

  They can produce crops of fruits and vegetables through tissue culture techniques.
• What is a key term associated with stem cells?

  Undifferentiated
• What is the role of adult stem cells?

  They can replace poorly functioning cells and make new blood and nerve cells.
• Why are embryos considered important in stem cell research?

  They are often used for research and can develop into various cell types.
• What are stomata?

  Tiny pores on the leaf surface that regulate gas exchange.
• How does diffusion work in leaves?

  Diffusion allows carbon dioxide to enter and oxygen to exit the leaf.
• What role do guard cells play in plants?

  They regulate the size of the stomatal pores.
• What happens to leaves when plants lose water?

  Leaves can wilt, reducing surface area and gas exchange.
• How do fish exchange gases?

  Fish use their gills for gas exchange.
• What is the function of gill filaments in fish?

  They allow oxygen to diffuse into the blood and carbon dioxide to diffuse out.
• What is required for active transport in cells?

  Energy is required to move substances against a concentration gradient.
• Give an example of active transport.

  The movement of glucose from the gut into the blood.
• What does selectively permeable mean in relation to the cell membrane?

  Only some substances can pass through it.
• What is diffusion?

  The movement of substances from a high concentration to a low concentration.
• What is the structure of the small intestine?

  The small intestine is a long tube with a great surface area lined with folds.
• What are villi?

  Microscopic finger-like projections that increase surface area for absorption.
• Why is a good blood supply important for villi?

  It helps in the efficient absorption of nutrients.
• Concentration


  The amount of particles (molecules or atoms) in a given area.
• Villi


  Villi are small, finger-like projections found in the small intestine that increase the surface area for absorption, allowing for more efficient absorption of nutrients from food.