B1 , B2, B3, B4 Flashcards
(24 cards)
What do plant cells have that animal cells do not?
Cell wall, chloroplasts, and a permanent vacuole.
What is the function of the mitochondria?
It is the site of aerobic respiration, which releases energy.
Describe how to prepare an onion cell slide.
Peel onion skin, place on slide, add iodine, cover with coverslip, view under microscope.
Why do we use stains like iodine in microscopy?
To highlight structures (e.g., nucleus, cell wall) that are otherwise hard to see.
What is mitosis and its purpose?
Mitosis is cell division to produce two identical daughter cells for growth and repair.
What are enzymes and what do they do?
Enzymes are biological catalysts that speed up reactions in the body.
What is the ‘lock and key’ model of enzyme action?
The enzyme’s active site fits a specific substrate like a key fits a lock.
What happens to enzymes at high temperatures or the wrong pH?
They become denatured; the active site changes shape and can’t bind the substrate.
Describe how to test the effect of pH on amylase.
Mix starch and amylase with buffer of different pH, test with iodine until no starch remains.
What is the function of bile in digestion?
It emulsifies fats and neutralises stomach acid to help enzyme action in the small intestine.
Name the four main types of pathogens.
Bacteria, viruses, fungi, and protists.
How do vaccines protect us?
They stimulate white blood cells to produce memory cells and antibodies.
Why don’t antibiotics work on viruses?
Viruses reproduce inside cells, and antibiotics can’t target them without damaging our cells.
What are the three ways white blood cells fight infection?
Phagocytosis, producing antibodies, and making antitoxins.
Why is it important to finish a full course of antibiotics?
To ensure all bacteria are killed and prevent resistant strains from surviving.
What is the word equation for photosynthesis?
Carbon dioxide + water → glucose + oxygen.
Name three factors that affect the rate of photosynthesis.
Light intensity, CO₂ concentration, and temperature.
Describe a test to measure photosynthesis using pondweed.
Count oxygen bubbles from pondweed under different light distances.
What is respiration and where does it happen?
It’s the process of releasing energy from glucose, mainly in the mitochondria.
What is the difference between aerobic and anaerobic respiration?
Aerobic uses oxygen; anaerobic does not and produces less energy.
Test for starch and its result?
Add iodine. Blue-black colour = starch present.
Test for glucose and its result?
Add Benedict’s solution and heat. Green/yellow/red = sugar present.
Test for protein and its result?
Add Biuret solution. Purple colour = protein present.
Test for lipids and its result?
Mix with ethanol, then water. Cloudy layer = lipids present.
