Topic 1 - Key Concepts In Biology Flashcards
What is the role of the nucleus?
Contains genetic material that control the activities of the cell.
What is the role of cytoplasm?
Gel-like substance that allows things to move around in the cell. Where most chemical reactions take place. Contains enzymes.
What is the role of the cell membrane?
Holds the cell together and controls what enters or leaves the cell
What is the role of the mitochondria?
Where respiration takes place
What is the role of ribosomes?
Involved in the translation of gentic material in the synthesis of proteins
What is the role of the cell wall?
Supports the cell and strengthens it
What is the role of the vacuole?
Contains cell sap, a weak solution of sugar and salt. It maintains the internal pressure to support the cell.
What is the role of the chloroplasts?
Where photosynthesis takes place
State 3 differences between plant and animal cells
Cell wall
Vacuole
Chloroplasts
State the equation for magnification
Magnification = image size / real size
Reminder: you need to know how to prepare a specimen for a microscope
CGP Page 14
What is the role of enzymes?
To speed up the ractions that take place in your body
State the 3 factors that affects the rate of enzyme-catalysed reactions
Temperature
pH
Substrate Concentration
What happens when an enzyme becomes denatured?
The active site of the enzyme changes shape, so it is no longer able to bind to the substrate.
What causes an enzyme to denature?
Every enzyme has an optimum temperature and pH. When the environment the enzyme changes too much from the optimum environment, it damages the enzyme, causing the enzyme to denature.
Why does temperature affect the rate of enzyme-catalysed reactions?
A higher temperature increases the rate at first because the enzymes have more energy. But if the temperature gets too high, some of the bongs holding the enzyme together break, causing the enzyme to denature.
Why does pH affect the rate of enzyme-catalysed reactions?
Every enzyme has an optimum pH. If the pH is too high or low, it interferes with the bonds holding the enzyme together, causing it to denature.
Which enzyme converts carbohydrates into simple sugars?
Carbohydrases
Which enzyme converts protein into amino acids?
Proteases
Which enzyme converts lipids into glycerol and fatty acids?
Lipases
State the equation for calculating energy in food
Energy in food = Mass of water(g) x Temperature change of water x 4.2
How do you find how much energy there is in food?
Burn the food under a boiling tube filled with water. Measure the temperature change and use the equation.
What is diffusion?
The net movement of particles from an area of higher concentration to an area of lower concentration. Happens in liquid and gases.
What is osmosis?
The net movement of water molecules across a partially permable membrane from a refion of higher water concentration to a region of lower concentration.
