topic 1 Flashcards
What is the function of the cell membrane?
It controls what enters and leaves the cell (selectively permeable)
Name three plant-only structures.
Cell wall, chloroplasts, permanent vacuole.
Where does photosynthesis happen?
In the chloroplasts (they contain chlorophyll to absorb light).
Name two structures found in both prokaryotic and eukaryotic cells.
Cell membrane and ribosomes
What does haploid mean?
A cell with half the normal number of chromosomes (e.g. gametes have one set).
How is an egg cell adapted?
Large cytoplasm with nutrients for embryo, haploid nucleus, jelly coat to protect and allow only one sperm to enter.
What are cilia?
Tiny hair-like structures that move substances along surfaces.
What is the purpose of ciliated epithelial cells in the airways?
They sweep mucus and trapped particles up and out of the lungs to keep them clean.
What is an advantage of electron microscopes?
They have higher resolution, so you can see smaller structures in more detail.
Why must microscopy samples be thin?
So light can pass through clearly to see detail.
What is the equation for size of specimen?
Size of specimen = image size ÷ Magnification.
How do you convert mm to μm?
Multiply by 1000 (1 mm = 1000 μm).
What is the standard form unit for micrometres?
μm = x 10⁻⁶ m.
What is the specific part of an enzyme that fits the substrate?
The active site.
Why don’t denatured enzymes work?
The active site changes shape, so the substrate no longer fits.
What happens to enzyme activity as temperature increases?
It increases to the optimum temperature, then drops if the enzyme denatures.
How do you investigate the effect of pH on amylase?
Add amylase to starch and buffer solution (different pHs), test with iodine to see how fast starch breaks down.
What are the products of lipid breakdown?
Fatty acids and glycerol.
What big molecule is made from simple sugars?
Starch (also glycogen or cellulose).
What is a positive result for Benedict’s test?
Blue turns brick red after heating (if reducing sugars are present).
How do you test for starch?
Add iodine solution – it turns orange to blue-black.
What is the test for lipids?
Add ethanol and water – it turns milky/cloudy if lipids are present.
How do you measure energy in a peanut?
Burn peanut under water and measure temperature rise to calculate energy released.
Define diffusion.
Movement of particles from high to low concentration.
Define osmosis.
Diffusion of water through a partially permeable membrane.
Define active transport.
Movement from low to high concentration using energy.
Why does a potato gain mass in an osmosis test?
Water moves into the potato cells from a dilute solution by osmosis, causing the cells to swell.
