KEY CONCEPTS

• what organelles can only be found in plant cells

  chloroplast, vacuole and cell wall
• how are bacteria cells different from animal/plant cells

  prokaryotic (no nucleus)
• what organelles can be found in bacteria cells only

  chromosomal dna

  plasmid (dna)

  flagellum
• what is chromosomal dna

  DNA found loose in the cytoplasm (since there is no nucleus)
• what is plasmid (dna)

  controls some cell activity alongside chromosomal dna
• what is a flagellum

  enables the bacteria cell to move
• how do bacteria cells reproduce/divide?

  binary fission
• what are specialised animal cells

  different types of cells that has adapted to do a particular role to ensure the organism functions as a whole
• what are the main 3 specialised cells

  egg cell, sperm cell, ciliated epithelial cell
• describe features of sperm cell

  needed for sexual reproduction

  • head contains a haploid nucleus
  • acrosome, needed to penetrate the egg's jelly coat in fertilisation
  • mitochondria for the sperm to release energy to swim to the egg
• describes the features of an egg cell

  needed for sexual reproduction

  • cytoplasm containing nutrients for the embryo and a haploid nucleus
  • jelly coat surrounding to protect the cell
• describe the features of epithelial cells

  located around the body (uterus, nose, etc)

  • cilia hairs to transfer particles
• what is a haploid

  a sex cell that contains one set of chromosomes (23)
• what are enzymes

  proteins needed for cell growth and repair
• enzymes are biological catalysts. what does this mean

  molecules that speed up a chemical reaction without being effected
• what is the lock and key hypothesis

  a model that demonstrates how the shape of an active site matches its own specific substrate molecule in enzymes
• what happens if an active site is damaged

  they denature and the substrate will no longer fit
• how can an active site be denatured/damaged?

  exposed to extreme levels of pH or temperature
• Why do we have digestive enzymes?

  to break down large food molecules into smaller molecules to pass to the blood
• what do carbohydrates break down into?

  starch inside carbohydrates is broken down by amylase and turned into glucose
• what do proteins break down into

  protein is broken down by protease into amino acids
• what are fats broken down into

  in fats, there are lipids that are broken down by lipase into fatty acids and glycerol
• where is amylase found in

  pancreas, saliva
• where is protease found in

  pancreas, stomach
• where is lipase found in

  pancreas and small intestines
• what is the optimum temperature/pH

  the best condition where enzymes work
• what happens if there is a high concentration of a substrate in an active site

  the enzyme activity will increase until it reaches a point and stays the same
• how would you calculate the rate of reaction

  amount of substrate used or product formed / time taken
• what is the method of investigating the effects of pH on enzyme activity

  method

  1.Drop one drop of iodine solution into each dimple tile

  2. Measure 2cm of amylase solution into a test tube

  3. Add 2cm of a buffer solution of a different pH level to the same test tube

  4. add another 2cm of starch into the mixture and start the stop clock and stir

  5. After 20 seconds, take a small amount of the mixture and start the stop clock. Place one drop of it on the first iodine drop on the dimple. Continue after each 20 seconds
• what does it mean if the iodine solution turns black/yellow? (in investigating enzyme activity)

  the starch has been digested
• what does independent variable mean

  what is changed in the experiment
• what is the dependent variable

  what is being measured
• what is the control variable

  what is kept the same
• what is diffusion

  movement of particles from an area of higher concentration to an area of lower concentration
• what is osmosis

  movement of WATER molecules across a semi-permeable membrane
• what factors can affect diffusion

  temperature, concentration and gradient
• what is active transport

  transport of molecules against their concentration gradient, from a low to high concentration
• how is active transport different to diffusion and osmosis?

  active transport needs energy
• what are the methods used to investigate osmosis in potatoes

  method:

  1.Set up a series of boiling tubes with a range of sucrose solutions with different concentrations

  2. Cut similar sized pieces of potato that will fit into a boiling tube

  3. Use a paper towel to dry the potato piece and measure its mass

  4. Place said potato pieces into a boiling tube, starting with the 0% sucrose solution for 20 minutes

  5. Remove the potatoe strip, drying it carefully while using a paper towel, and measure the mass of the potato strip.

  6. Repeat for each concentration