AQA GCSE Biology Paper 1 Flashcards

Questions and Answers

What is the magnification equation?

Magnification = image size / actual object size

How many micrometers (um) are in 1 millimeter (mm)?

1000 um

How many nanometers (nm) are in 1 micrometer (um)?

1000 nm

Why can we see the nucleus and cell wall with a light microscope but not the mitochondria?

Too small and not stained Signup and view all the answers

How can we see smaller parts of cells?

An electron microscope has much more resolution and magnification Signup and view all the answers

What is osmosis?

The movement of water from an area with high concentration of water to an area of low concentration of water Signup and view all the answers

What is a solute?

Something that dissolves in water Signup and view all the answers

What are the results of investigating osmosis?

High concentration of sugar in solution - water moves out of potato cells into the solution; potato gets smaller. Low concentration - potato gets bigger. Signup and view all the answers

What are the control variables in investigating osmosis?

Amount of solution Signup and view all the answers

Why should you remove excess water with paper towels before weighing in osmosis experiments?

To ensure that any change in the mass of the potato is due to a change in the water content inside the potato cells Signup and view all the answers

How do you test for starch?

Add iodine to substance; turns black if starch is present Signup and view all the answers

How do you test for protein?

Add biuret; turns purple Signup and view all the answers

How do you test for reducing sugar?

Add Benedict's solution and heat for 2 minutes; turns red Signup and view all the answers

How do you test for lipids?

Add ethanol then add water; turns cloudy Signup and view all the answers

Why do you need a water bath when investigating amylase enzyme?

To maintain the correct temperature, because temperature affects reaction rate Signup and view all the answers

Why might the exact optimum pH not be determined when testing amylase enzyme across various pH levels?

Because although two answers may both show quick reactions, the actual optimum could be between those numbers Signup and view all the answers

What are sources of error and weaknesses when investigating amylase enzyme?

Measuring, starting and stopping timers Signup and view all the answers

What is the effect of light on photosynthesis?

The closer the lamp, the quicker the bubbles are produced, hence a higher rate of photosynthesis Signup and view all the answers

Why might results of photosynthesis experiments be inaccurate?

Difficult to count very small bubbles; each bubble counts as 1 no matter how big it is Signup and view all the answers

Why should you leave the plant for a few minutes before starting to count bubbles in photosynthesis experiments?

It takes time for the plant to adjust to the light/temperature and for photosynthesis to reach the correct rate Signup and view all the answers

How can you avoid heat from the lamp being a source of error in photosynthesis experiments?

Place a glass screen in front of the beaker so the light gets through but the heat doesn't Signup and view all the answers

What are the other limiting factors for photosynthesis apart from light?

The plant also needs enough temperature and CO2 Signup and view all the answers

Why do you have to repeat the reaction time investigation?

So you can calculate the mean, range of results, and resolution of measurements Signup and view all the answers

What apparatus should you use to measure population size?

A quadrat Signup and view all the answers

What is a cell membrane important for?

Determines what goes in and out of the cell Signup and view all the answers

What is a cell wall important for?

Structure Signup and view all the answers

What is the vacuole important for?

Structure Signup and view all the answers

What happens in the cytoplasm?

Reactions Signup and view all the answers

What are ribosomes responsible for?

Protein synthesis Signup and view all the answers

What is produced at the mitochondria?

Energy Signup and view all the answers

Name all the components in an animal cell.

Cell membrane, mitochondria, ribosomes, cytoplasm, nucleus Signup and view all the answers

What is present in a plant cell but not in an animal cell?

Cell wall, vacuole, chloroplasts Signup and view all the answers

Name all parts of a bacterial cell.

Cell membrane, cytoplasm, chromosomes, flagella, ribosomes, cell wall Signup and view all the answers

How does a cell specialize?

All start off looking the same; various differentiation occurs. Signup and view all the answers

Study Notes

Microscopy

Magnification equation: Magnification = image size / actual object size.
1 mm equals 1000 micrometers (um).
1 um equals 1000 nanometers (nm).
Light microscopes can visualize nuclei and cell walls, but not mitochondria due to their small size and lack of staining.
Electron microscopes provide higher resolution and magnification for viewing smaller cellular components.

Osmosis

Osmosis defined as the movement of water from high to low concentration areas.
Solute: A substance that dissolves in water.
In osmosis investigations: high sugar concentrations lead to water leaving potato cells, resulting in smaller potatoes; low concentrations cause potato cells to swell.
Control variable in osmosis experiments includes the amount of sugar solution used.
Excess water on potato samples before weighing must be removed to accurately assess changes in water content.

Testing for Biological Molecules

Starch test: Add iodine; turns blue-black if starch is present.
Protein test: Add biuret reagent; turns purple if protein is present.
Reducing sugar test: Add Benedict's solution and heat for 2 minutes; turns red if reducing sugars are present.
Lipid test: Add ethanol followed by water; turns cloudy if lipids are present.

Enzyme Investigations

A water bath is used to maintain a constant temperature during amylase enzyme investigations, as temperature affects reaction rates.
Testing different pH levels may not yield the exact optimum pH because the actual optimum could lie between tested values.
Common errors in enzyme experiments arise from inaccurate measurements and timing.

Photosynthesis

Closer light sources result in a faster bubble production rate, indicating a higher rate of photosynthesis.
Inaccurate results in counting bubbles may occur due to size variability; all bubbles count as one, regardless of size.
Allowing time for plants to acclimate to light and temperature ensures accurate photosynthesis rates.
To reduce heat interference from light sources, a glass screen can be used to allow light but block heat.
Photosynthesis is also limited by temperature and carbon dioxide levels, which can prevent rates from increasing despite maximal light availability.

Population Sampling

When measuring population size, a quadrat is the recommended apparatus for sampling.

Cell Structure and Function

Cell membranes regulate the passage of substances in and out of cells.
Cell walls provide structural support in both plant cells and prokaryotes.
The vacuole in plant cells stores nutrients and maintains turgor pressure.
Ribosomes are responsible for synthesizing proteins.
Mitochondria are the sites of energy production.
Animal cells contain membranes, mitochondria, ribosomes, cytoplasm, and nuclei.
Plant cells have additional structures: cell walls, vacuoles, and chloroplasts.
Bacterial cells include membranes, cytoplasm, chromosomal DNA, flagella, ribosomes, and cell walls.

Cell Specialization

Cells initially possess similar structures but differentiate based on function, adapting features suitable for their specific roles.

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Description

This quiz consists of flashcards covering key concepts from the AQA GCSE Biology Paper 1 syllabus. It addresses important topics such as magnification equations, the measurement units used in light microscopy, and the visibility of cellular structures. Test your knowledge and prepare for your exam effectively with these concise definitions.