Biology paper 1

• What is the purpose of the cell membrane in a plant cell?

  It determines which substances enter and exit the cell.
• What is the function of the cell wall in a plant cell?

  It provides structural support.
• What is the role of the vacuole in a plant cell?

  It is important for structure and storage.
• Where do most cellular reactions take place in a plant cell?

  In the cytoplasm.
• What are ribosomes responsible for in a plant cell?

  Protein synthesis.
• What is the function of chloroplasts in a plant cell?

  They are involved in photosynthesis.
• What is the role of mitochondria in a plant cell?

  Energy production.
• What is the function of the nucleus in a plant cell?

  It holds the DNA and acts as the control center.
• What is a key difference between plant and animal cells?

  Plant cells have a cell wall, vacuole, and chloroplasts.
• What is the function of the bacterial cell membrane?

  It controls what goes in and out of the cell.
• Where is the DNA located in a bacterial cell?

  In the chromosome, not in a nucleus.
• What is the role of flagella in a bacterial cell?

  It is used for locomotion.
• What is cell differentiation?

  It is the process where cells become specialized for specific functions.
• What are the specialized cells in the human body?

  • Muscle cells: contract and stretch
  • Neurons: transmit signals
  • Villi cells: increase surface area for absorption
  • Skin cells: provide protection
• What is the basic structure of a cell?

  All cells have a cell membrane, cytoplasm, and genetic material.
• How do microscopes vary in complexity?

  They range from basic hand-held lenses to advanced electron microscopes controlled by computers.
• How do you calculate magnification from an image taken with a microscope?

  Magnification = image height / object height.
• What is a micrometer in meters?

  1 micrometer = $1 \times 10^{-6} \text{ meters}$.
• What is a nanometer in meters?

  1 nanometer = $1 \times 10^{-9} \text{ meters}$.
• What is a picometer in meters?

  1 picometer = $1 \times 10^{-12} \text{ meters}$.
• How do enzymes function?

  They have specific active sites that bind to substrates to form enzyme-substrate complexes.
• What happens to enzymes at low temperatures?

  They have insufficient energy to function effectively.
• What is the optimal temperature for enzyme activity?

  It is the temperature at which enzymes function most efficiently.
• What does denaturation mean for enzymes?

  It means the enzyme's structure is altered, affecting its function.
• How does pH affect enzyme activity?

  Extreme pH levels can denature enzymes, affecting their active sites.
• What happens when all active sites on an enzyme are occupied?

  Enzyme activity cannot increase further despite increased substrate concentration.
• What does lipase do?

  It breaks down fats into fatty acids and glycerol.
• Where is lipase produced?

  In the pancreas and small intestine.
• What does protease do?

  It breaks down proteins into amino acids.
• Where is protease produced?

  In the stomach, pancreas, and small intestine.
• What does amylase do?

  It breaks down starch into sugars.
• Where is amylase produced?

  In the salivary glands, pancreas, and small intestine.
• What is diffusion?

  It is the movement of substances from high to low concentration.
• How does diffusion occur in the lungs?

  Oxygen diffuses from the lungs into the blood, and carbon dioxide diffuses from the blood into the lungs.
• What is osmosis?

  It is the movement of water through a partially permeable membrane from high to low water concentration.
• What is active transport?

  It is the movement of substances from low to high concentration against the concentration gradient.
• How do stem cells function?

  They have the potential to differentiate into any type of cell.
• What are the uses of stem cells?

  They can be used to grow new brain cells, bones, or organs.
• What is the controversy surrounding stem cell research?

  It involves ethical concerns about creating and destroying human embryos.
• What does the central nervous system consist of?

  It consists of the brain and spinal cord.