Cells
Where is DNA stored in a cell?
Nucleus
What is the lens called that can be changed to increase or decrease magnification?
Objective lens
Diffusion is the net movement of ___________.
Particles
Water
What type of biological molecule is an enzyme and what is this composed of?
Protein - composed of amino acids.
Vacuole, cell wall, chloroplast
Eyepiece x Objective = Total Magnification
Movement of particles from a high to lower concentration, until equilibrium.
Active transport requires energy but diffusion does not.
In active transport, substances move against the concentration gradient (low to high).
Why will enzymes work only on one substrate?
The active site is shaped to fit the substrate, so no others will fit.
Which process takes place in chloroplasts?
Photosynthesis
Which objective should you start with when viewing a slide under a microscope?
The lowest one (usually x4)
Diffusion is a passive process. What does this mean?
It does not require energy.
Fully explain the process of osmosis.
Movement of water molecules.
From high to low WATER concentration.
Across a semi/partially permeable membrane.
Until equilibrium.
HIGH temperatures and EXTREME pH.
Explain how an egg cell is specialised to suit its function.
Lots of mitochondria to generate energy/ATP, which supports the developing young.
Specialised cell membrane which changes to block entry to further sperm after fertilisation.
Which chemical is used to stain cheek cells when viewing under the microscope?
Methylene blue
Give one example of where diffusion happens in the body.
Nutrients diffusing from the small intestine into the bloodstream.
Carbon dioxide diffusing from the bloodstream into alveoli.
Oxygen diffusing from alveoli into the bloodstream.
Give an example of a substance that moves via active transport and where this occurs.
Mineral ions moving from soil into root hairs.
What does it mean if an enzyme has been denatured?
Its active site has changed shape so it will no longer fit its substrate.
Explain the adaptations a plant cell has that allow it to function.
Chloroplasts are present to allow photosynthesis, they have cell walls to provide structure and support and they have vacuoles as a means of storing sap.
Outline one hazard and related control measure for making either cheek or onion slides to view using a microscope?
Methylene blue and iodine are irritants - wear goggles.
Cheek cells are a biohazard - dispose of swabs immediately.
Coverslips break break easily and are sharp - hold carefully by the corner.
Explain in detail why increasing the temperature affects the rate of diffusion (3).
Particles gain kinetic energy when heated.
This means they move faster.
Which speeds up the rate of diffusion.
Give two examples where osmosis occurs.
Water moving from soil into root hairs.
Water moving from the large intestine into the bloodstream.
Outline the lock and key hypothesis (6).
Substrate enters the enzyme's active site.
To form the enzyme-substrate complex.
The enzyme converts the substrate into the product.
Which forms the enzyme-product complex.
The product is a different shape to the substrate.
So doesn't fit the active site and is released.