Living together - Food and ecosystems

Plants make their own food using photosynthesis. The food is important for the plants and for organisms that feed on the plants. Optimum rates of photosynthesis produce maximum plant yields.

For an organism to function, substances must move into and out of cells. Three processes contribute to this movement – diffusion, osmosis and active transport.

During transpiration plants move water from the roots to their leaves in xylem vessels. Glucose made in the leaves through photosynthesis is then moved to all cells in phloem vessels by translocation.

Carbohydrates, proteins and lipids are required by humans. The digestive system breaks down large molecules. Nutrients are passed to other organisms in a food web. Enzymes are biological catalysts.

Plants compete for light, water, minerals and space. Animals compete for food, mates and territory. Decay is the breakdown of organic matter and is affected by temperature, water and oxygen.

The abundance of organisms in an ecosystem is dependent upon biotic (living) and abiotic (non-living) factors. Abundance and distribution are estimated using techniques such as transects and quadrats.

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