Topic 1 - Cell Biology

• What are eukaryotes?

  cells with a nucleus
• What are prokaryotes?

  unicellular organisms that lack a nucleus
• What three things do plant cells have that animal cells don't?

  - Plant cells have cell walls

  - Plant cells have a permanent vacuole

  - Plant cells have chloroplasts
• What is the function of the nucleus?

  Contains the cell's genetic material.
• What is the function of the cytoplasm?

  Where most chemical reactions take place
• What s the function of the cell membrane?


  controls what substances can come in and out of the cell
• What is the function of the mitochondria?

  releases energy during aerobic respiration
• What is the function of the cell wall?

  to protect and support the cell
• What is the function of a vacuole?

  Contains cell sap
• Are plant and animal cells prokaryotic or eukaryotic?

  Eukaryotic
• Are bacterial cells prokaryotic or eukaryotic?

  Prokaryotic
• Where is the genetic material found in animal cells and bacterial cells?

  - animal cells, nucleus

  - bacterial cells, cytoplasm
• What is resolution?


  The ability to clearly distinguish the individual parts of an object
• What is magnification?


  How many times larger the image is than the object
• Which gives a higher resolution - a light microscope or an electron microscope?

  electron microscopes
• What is diffusion?


  The movement of particles from an area of high concentration to an area of low concentration.
• What factors affect the rate of diffusion?

  Temperature, surface area, difference in concentration
• Which molecules are able to diffuse into and out of cells?

  glucose, water, amino acids
• Describe the cell cycle

  1. Cell Growth

  - DNA is duplicated

  
  

  2. Mitosis

  - Nucleus splits into two

  
  

  3. Cytokinesis

  - Cytoplasm divides and two identical daughter cells are produced
• What is osmosis?


  diffusion of water across a partially permeable membrane
• What is a partially permeable membrane?

  A membrane that has very small holes that only small molecules can pass through them and bigger molecules cant
• What is the function of root hair cells?

  To absorb water and mineral ions from the soil
• What is active transport?

  the movement of molecules across a cell membrane, from regions of low concentration to a region of high concentration by the using energy from cellular respiration.
• How do root hair cells take in minerals?

  Active transport. This process allows the plant to absorb minerals against a concentration gradient, which is essential for growth.
• How is active transport used in the gut?

  It allows nutrients to be taken into the blood, despite the fact that the concentration gradient is the wrong way
• What does how easy it is for an organism to exchange substances with its environment depend on?

  Its surface area to volume ratio
• Why do multicellular organisms need exchange surfaces?

  They have a smaller surface area compared to their volume so not enough substances can diffuse from their outside surface to supply their entire volume.
• How are exchange surfaces adapted to maximise effectiveness?

  - thin membrane so substances only have a short distance to diffuse

  - large surface area so lots of substances can diffuse at once

  - exchange surfaces in animals have lots of blood vessels to get stuff in and out of the blood quickly

  - gas exchange surfaces in animals are often ventilated so air moves in and out
• Where does gas exchange occur?

  lungs
• What is the job of the lungs in gas exchange?

  To transfer oxygen to the blood and to remove waste carbon dioxide from it
• Where is the aveoli found and what is it's function?

  found in the lungs. it's function is to exchange oxygen and carbon dioxide
• Where is the villi found and what is it's function?

  found in the small intestine. absorb nutrients e.g. glucose and amino acids
• What are the 5 main features of specialised exchange surfaces?

  - large surface area, lots of molecules can diffuse across at same time

  - very thin surfaces, substances have a short diffusion distance

  - permeable surfaces, substances are able to pass through

  - good supply of blood, maintains strong concentration gradient

  - good supply of external medium, maintains a strong concentration gradient
• How is a leaf adapted for gas exchange?

  - Large surface area to absorb light and carbon dioxide

  - Thin and flat so short diffusion distance for carbon dioxide and oxygen

  - Lots of chloroplasts containing chlorophyll for photosynthesis
• How is the structure of a gill adapted for effective gas exchange?

  - thin surface layer to minimise the distance that the gases have to diffuse

  - a large concentration gradient is maintained between the water and the blood

  - it is made up of gill filaments which give a large surface area
• What is cell differentiation?

  The process in which cells become specialized.
• What is the function of a sperm cell?

  To get the male DNA to the female DNA
• How are sperm cells specialised for reproduction?

  - long tail to help it swim to the egg

  - lots of mitochondria to provide the energy needed

  - carries enzymes in its head to penetrate the egg
• What is the function of nerve cells?

  To carry electrical impulses from one part of the body to another
• How are nerve cells specialised for rapid signalling?

  - long, to cover more distance

  - branched connections at their ends to connect to other nerve cells