An ecosystem that is man-made e.g. fish farms and forestry plantations.

They have a low biodiversity.

An ecosystem that occurs naturally e.g. woodland or a lake.

They have a high biodiversity.

A small jar used for collecting insects.

It has two tubes: one to apply suction with your mouth (a fine mesh is placed over the end to avoid insect consumption) and one to suck the insect into the jar.

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Used to sample small invertebrates living on the ground e.g. beetles, spiders and slugs.

A container buried in the ground with its top level with the soil's surface, covered by a piece of wood with a gap for insects to climb in.

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Used to identify and count organisms, usually plants.

A wire square containing smaller areas, such as 5x5 or 10x10 grids.

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Capture-recapture method

- Equation?

- How?

- Assumptions?

Population size =

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Animals are collected and counted, marked and then released. A few days later the amount of marked animals are counted to estimate the population size.

Assumptions have to be made:

- No deaths occurred.

- Sample methods used are identical.

- Marking has not affected the survival rates of the animals.

- Maps the distribution of organisms.

- A long length of string is laid across an area, a quadrat is placed at regular intervals to record the amount of organisms.

- Data is displayed as a kite diagram.

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- The distribution of organisms.

- Can be shown using a transect line.

- Changes in abiotic (not biological) factors e.g. trampling near a footpath can affect zonation.

Photosynthesis 

 - Word equation?

- Balanced symbol equation?

Word equation:

Carbon Dioxide + Water [image] Glucose + Oxygen

Symbol equation:

6CO₂ + 6H₂O [image] C₆H₁₂O₆ + 6O₂

Glucose

- What is it?

- What is it used for?

- What can it be converted into?

- Simple sugars.

- Used for respiration, releasing energy.

- Can be converted into:

> Cellulose - to make cell walls.

> Proteins - for growth and repair.

> Starch, fats and oils - for storage.

Starch

- Why is it used for storage?

- It is insoluble.

- Does not move from storage areas.

- Does not affect the water concentration of cells and cause osmosis (unlike glucose).

Photosynthesis

- What are the processes for it to occur?

- It is a two-stage process.

- Water is split up by light energy releasing oxygen gas and hydrogen ions.

- Carbon dioxide gas combines with the hydrogen ions to produce glucose and water.

Historical understanding of photosynthesis

- What did Greek scientists believe?

- What did Van Helmont conclude?

- What did Priestley's experiment show?

- What have modern experiments shown?

- Greek scientists believed that plants took minerals from the soil to grown and gain mass.

- Van Helmont concluded that plant growth could not only be due to uptake of soil minerals, shown by an experiment of growing a willow tree.

- Priestley's experiment showed that plants produce oxygen.

- Modern experiments using a green algae called Chlorella and an isotope of oxygen, ¹⁸O, as part of a water molecule. It is shown that light energy is used to split water into oxygen gas and hydrogen ions, not carbon dioxide.

Photosynthesis

- What factors affect the rate?

- When does it occur?

- Can be affected by:

> Carbon dioxide levels

> Light intensity

> Temperature

- More carbon dioxide = increased rate.

- More light = increased rate.

- Higher temperature = increased rate due to increase in enzyme action.

- Lack of the factors affecting rate are called limiting factors.

 - Only occurs during daytime.

Leaf structure

- How are the layers structured? (What order?)

- What are the adaptations?

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- Contains many specialised cells, adapted for efficient photosynthesis.

- Outer epidermis = lacks chloroplasts, transparent, allows light to enter.

- Upper palisade layer = contains chloroplasts, receive the most amount of light.

- Spongy mesophyll cells = loosely spaced to allow diffusion between cells, creates a large surface area/volume ratio.

- Stomata = control water loss and gas exchange by opening and closing, allows carbon dioxide to diffuse into leaf.

- Guard cells = Control the opening and closing of the stomata.

Vascular bundles (veins)

- What do they do?

- What are the two cells they consist of?

What are their purposes?

- Support the leaf, transports water and carbohydrates.

- Xylem and phloem cells that form continuous bundles from the roots to the stem and leaves.

- Xylem = carry water and minerals from the root to the leaves.

- Phloem = carry dissolved food e.g. sugars from the leaves to other parts of the plant via translocation.

Transpiration

- What is it?

- How does it work?

- The evaporation of water from leaves.

- Takes place from the surface of the plant leaves.

- Process:

> Water enters plant through root hairs.

> Water travels up stem.

> Some water is used in photosynthesis.

> Some water escapes by transpiration.

Photosynthetic pigments

- What are they called?

- What do they do?

- Absorb light, maximising the use of energy from the Sun.

- Chlorophyll a = main pigment, absorbs light mainly in the red and blue regions of the spectrum.

- Chlorophyll b, xanthophyll and carotene = accessory pigments, absorb light from the other regions of the spectrum and passes the energy onto chlorophyll a.

Xylem and Phloem

- What are they made of?

- Xylem:

> Cellulose of cell wall has extra layers made up of a chemical called lignin.

> Very strong.

> Cells die, making long, thin tubes with a hollow lumen.

> The cells are called vessels.

- Phloem:

> Cells are long and thin, forming columns.

> Stay alive to be able to pass chemicals from cell to cell.

Diffusion

- What is it?

- How are leaves adapted to increase the rate?

- How is the rate of diffusion increased?

- The net movement of particles in a gas/liquid from an area of high concentration to an area of low concentration caused by random movement of particles.

- Leaves are adapted by:

> A large surface area.

> Stomata, which are spaced out.

> Gaps between the spongy mesophyll cells.

- Rate of diffusion is increased by:

> A shorter distance for the molecules to travel.

> A steeper concentration gradient (a greater difference in concentration between the two areas).

> A greater surface area for the molecules to diffuse from, or into.

Osmosis

- What is it?

- What happens in plant cells?

- What happens in animal cells?

- A type of diffusion that involves the random movement of water molecules.

- The movement of water across a partially-permeable membrane from an area of high water concentration to an area of low water concentration.

- In plant cells:

> Too much water = cells swells up, increase in water pressure against cell wall which is called turgor pressure causing the cell to become turgid (hard and rigid).

> Too little water = cells collapse, contents become plasmolysed, decrease in water pressure, cell becomes flaccid and the plant wilts.

- In animal cells:

> Too much water = cell swells up and bursts (lysis) due to lack of cell wall.

> Too little water = cell shrinks (crenation).

Minerals

- Why are they needed?

- Which minerals are needed for plant growth?

- Purpose of the minerals?

- Mineral deficiency?

- Needed for the plants to survive and grow.

- Minerals needed:

> Nitrates (Nitrogen, N) - proteins for amino acids, for cell growth.

> Phosphates (Phosphorus, P) - makes DNA and cell membranes, for respiration and growth.

> Potassium compounds (Potassium, K)- increases enzyme action, for photosynthesis and respiration.

> Magnesium compounds (Magnesium, Mg) - makes chlorophyll, for photosynthesis.

- Poor plant growth is caused by a deficiency of a mineral.

- Symptoms:

> Nitrate - poor growth, yellow leaves.

> Phosphate - poor root growth, discoloured leaves.

> Potassium - poor flower and root growth, discoloured leaves.

> Magnesium - yellow leaves.

Mineral uptake

- Process?

- Active transport?

- Taken up by root hair cells by active transport, a system of carriers transport selected minerals across the cell membrane.

- Enables minerals, present only in low concentrations, to enter root hairs already containing higher amounts of minerals.

- Uptake of minerals against a concentration gradient requires energy from respiration.

- Organisms that feed on dead and decaying material (detritus) e.g. earthworms, maggots and woodlice.

- They increase the rate of decay by breaking up the detritus, increases surface area for breakdown.

Decay

- How can the rate be increased?

- Factors that increase rate:

> Temperature = optimum temperature (bacteria = 37°C, fungi = 25°C), too high temperature denatures enzymes.

> Oxygen = more oxygen.

> Water = more water.

> Presence of microorganisms.

Preserving food

- Methods?

- Methods:

> Canning - food is heated, kills bacteria, sealed in a vacuum to prevent entry of oxygen and bacteria.

> Cooling - slows down bacterial and fungal growth and reproduction.

> Freezing - kills some bacteria and fungi, slows down growth and reproduction.

> Drying - removes water so bacteria cannot feed and grow.

> Adding salt/sugar - kills some bacteria and fungi, removes water by osmosis.

> Adding vinegar - produces very acidic conditions killing most bacteria and fungi, reduces pH.

Pesticides

- Types?

- Disadvantages?

- Types: insecticides, fungicides and herbicides.

- Disadvantages:

> Can enter and accumulate in food chains, causing lethal dose to predators.

> Can harm other organisms that live nearby which are not pests.

> Some are persistent, take a very long time to break down.

- Advantages:

> Does not use artificial fertilisers or pesticides.

> Uses animal manure and compost.

> Uses crop rotation: nitrogen-fixing crops and varying seed planting times to get a longer crop time.

> Thought to be healthier and tastier.

- Disadvantages:

> Crops are smaller.

> Produce more expensive.

- Uses living organisms to control pests.

- Alternative to pesticides.

- Examples: ladybirds to eat aphids, which damage plants.

- Can cause problems:

> Introduced species eating other useful species.

> Rapid increase in population of introduced species.

> Example: Cane toads in Australia.

- Uses artificial fertilisers and pesticides.

- Efficient in producing large crop yields cheaply.

- Keeping animals inside sheds/barns (battery farming) = use less energy to keep warm and move, more energy on growth or production.

- Plants grown in water containing minerals.

- Usually occurs in glasshouses or polytunnels.

- A type of intensive farming, useful in areas of barren soil or low rainfall.

- Tomatoes are a common crop.

- Better control over mineral levels and disease.

- Artificial fertilisers are used.

- Very expensive.

- Thin = short distance for carbon dioxide to diffuse

- Contains chlorophyll and other pigments = absorbs light from different parts of the Sun's spectrum.

- Vascular bundles = supports the leaf, transports water and carbohydrates.

- Stomata = allows carbon dioxide to diffuse into the leaf.

- Guard cells = controls opening and closing of stomata depending on conditions.