6 Markers Flashcards
(19 cards)
Describe how to prepare and use a microscope to observe biological specimens.
1 – Place a thin sample of specimen on a clean slide.
2 – Add a drop of stain to make structures more visible.
3 – Carefully lower a coverslip to avoid air bubbles.
4 – Place the slide on the stage and select low power objective lens.
5 – Use the coarse focus, then fine focus to sharpen the image.
6 – Switch to higher magnification for more detail if needed.
Describe how to investigate the effect of pH on enzyme activity.
1 – Prepare test tubes with buffer solutions at different pH values.
2 – Add equal volumes of enzyme and substrate to each tube.
3 – Use a water bath to maintain a constant temperature.
4 – Test for the end of the reaction using iodine or colour change.
5 – Record time taken for the reaction to complete.
6 – Determine optimum pH by comparing rates across pH values.
Describe how to identify biological molecules using chemical reagents.
1 – Test for sugars with Benedict’s solution and heat.
2 – Test for starch with iodine solution.
3 – Test for proteins with Biuret solution.
4 – Test for lipids using ethanol and water (emulsion test).
5 – Observe and record the colour change in each test.
6 – Ensure safety and consistent sample quantities for reliability.
Describe how to investigate osmosis in plant tissue.
1 – Cut identical pieces of potato and blot dry.
2 – Measure and record their initial mass.
3 – Place pieces in different concentrations of sugar solution.
4 – Leave for the same amount of time.
5 – Remove, dry, and reweigh the pieces.
6 – Calculate percentage mass change and plot against concentration.
Describe how to investigate the effect of antibiotics or antiseptics on bacterial growth.
1 – Pour nutrient agar into Petri dishes using aseptic techniques.
2 – Spread bacteria evenly across the agar surface.
3 – Place discs soaked in antibiotics or antiseptics on the agar.
4 – Seal and incubate at 25°C for 48 hours.
5 – Measure the diameter of inhibition zones around each disc.
6 – Compare results to identify the most effective substance.
Describe how to investigate the effect of light intensity on the rate of photosynthesis.
1 – Place pondweed in a beaker with sodium hydrogencarbonate.
2 – Set up a light source at a fixed distance.
3 – Count the number of oxygen bubbles released per minute.
4 – Repeat at different distances to vary light intensity.
5 – Keep temperature and carbon dioxide concentration constant.
6 – Plot rate of photosynthesis against light intensity.
Describe how to investigate respiration in living organisms.
1 – Place living organisms in a sealed container with a capillary tube.
2 – Add soda lime to absorb carbon dioxide.
3 – Include a coloured liquid in the capillary tube.
4 – Measure movement of the liquid over a set time.
5 – Keep temperature and mass of organisms constant.
6 – Greater movement of liquid indicates higher respiration rate.
Describe how to investigate the distribution of organisms using quadrats and transects.
1 – Stretch a transect line across a habitat.
2 – Place quadrats at regular intervals along the transect.
3 – Count and record species within each quadrat.
4 – Measure abiotic factors (e.g., light, moisture) at each point.
5 – Repeat the sampling for reliability.
6 – Analyze patterns and how species distribution changes.
Describe how the nervous system responds to stimuli.
1 – A stimulus is detected by a receptor.
2 – Sensory neurons carry the impulse to the CNS.
3 – The CNS processes the information.
4 – Motor neurons carry the impulse from the CNS to an effector.
5 – The effector (muscle or gland) produces a response.
6 – This forms a coordinated response to maintain homeostasis.
Explain how reflex actions differ from normal responses.
1 – Reflexes are automatic and rapid.
2 – They do not involve conscious decision-making.
3 – The impulse travels via a reflex arc.
4 – Sensory neurons connect to relay neurons in the spinal cord.
5 – Relay neurons pass impulses to motor neurons.
6 – This helps protect the body from harm.
Explain how the body maintains blood glucose levels.
1 – The pancreas detects changes in blood glucose.
2 – High glucose triggers insulin release.
3 – Insulin stimulates glucose uptake by cells and storage as glycogen.
4 – Low glucose triggers glucagon release.
5 – Glucagon causes glycogen to convert to glucose in the liver.
6 – This maintains blood glucose within a narrow range.
Describe the hormonal control of the menstrual cycle.
1 – FSH stimulates the growth of follicles in the ovaries.
2 – Follicles release oestrogen to thicken the uterus lining.
3 – High oestrogen triggers LH release.
4 – LH causes ovulation – release of an egg.
5 – The corpus luteum secretes progesterone.
6 – Progesterone maintains the uterus lining in case of pregnancy.
Explain how vaccination protects against infectious disease.
1 – Vaccines contain dead or weakened pathogens.
2 – The immune system produces antibodies in response.
3 – Memory cells are also produced.
4 – These allow a faster response if exposed again.
5 – The pathogen is destroyed before causing illness.
6 – Herd immunity protects unvaccinated individuals too.
Describe how lifestyle choices affect the risk of cardiovascular disease.
1 – Saturated fats increase cholesterol and cause artery blockages.
2 – Smoking damages artery walls and raises blood pressure.
3 – Lack of exercise leads to obesity.
4 – Excess alcohol raises blood pressure and damages the heart.
5 – Stress can lead to unhealthy behaviours.
6 – These combined factors raise the risk of heart disease.
Explain how water moves through a plant.
1 – Water enters root hair cells by osmosis.
2 – It passes through the cortex to the xylem.
3 – Water travels up the xylem vessels.
4 – Transpiration causes water to evaporate from leaf stomata.
5 – This creates a pull on the water column.
6 – Cohesion and adhesion help move water upward.
Explain how energy is transferred through a food chain.
1 – Producers convert light into chemical energy.
2 – Primary consumers eat producers and gain energy.
3 – Secondary and tertiary consumers follow.
4 – Energy is lost at each level via heat, respiration, and waste.
5 – Only a small percentage is transferred to the next level.
6 – This limits the length of food chains.
Describe the stages of the carbon cycle.
1 – Plants absorb CO₂ during photosynthesis.
2 – Animals eat plants and pass on carbon.
3 – Respiration by organisms releases CO₂ back to the air.
4 – Decomposers break down dead organisms, releasing CO₂.
5 – Combustion of fossil fuels releases stored carbon.
6 – The cycle ensures carbon is continuously recycled.
Explain how selective breeding is used in agriculture.
1 – Humans select individuals with desirable traits.
2 – These individuals are bred together.
3 – Offspring with the best traits are selected again.
4 – The process repeats over many generations.
5 – Desired traits become more common in the population.
6 – This improves yield, disease resistance, or other qualities.
Explain the process of natural selection.
1 – Variation exists within a population due to mutations.
2 – Some individuals have advantageous traits.
3 – These individuals are more likely to survive and reproduce.
4 – Their beneficial genes are passed to offspring.
5 – Over time, the trait becomes more common.
6 – The population evolves to be better adapted.
