B2 biology

different topics for biology unit 2

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Cells

The differences between plant and animal cells and structure and function of the cell parts including the cell membrane, cytoplasm, nucleus, ribosomes, mitochondria, and in plant cells, chlorplasts large vacuole and cell wall.

The chemical reactions inside the cells are controlled by enzymes.

Plant and animal cells are specialised to perform specific functions and to relate specialised structure to function and how that relates to the functions of tissues and organs.

Substances can move in and out of cells by diffusion and osmosis. Diffusion is the spreading of particles of a gas, or of any substance in solution, resulting in a net movement from a region where they are of a higher concentration.

The factors that affect the rate of diffusion. The greater the difference in concentration, the faster the rate of diffusion. Oxygen required for respiration passes through cell membranes by diffusion.

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The symptons shown by plants growing conditions where mineral ions are deficient including stunted growth if nitrate ions are deficient and yellow leaves if magnesium ions are different.

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Osmosis is the diffusion of water from a dilute to a more concentrated solution through a partially permeable membrane that allows the passage of water molecules but not solute particles.

Differences in concentrations of the solution inside and outside a cell cause water to move into or out of the cell by osmosis. Distinguish between diffusion and osmosis and the importance of osmosis in plants and animals.

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Plants

Photosynthesis is a chemical reaction that takes place in the chloroplasts of plant cells using light energy to convert carbon dioxide and water into oxygen and glucose.

The rate of photosynthesis may be limited by low temperature and the shortage of carbon dioxide or light and these factors interact. If any of these factors are in short supply, the rate of photosynthesis is limited.

Glucose produced in photosynthesis may be converted into insoluble starch for storage. Plant cells use some of the glucose produced during photosynthesis for respiration. Glucose combines with nitrogen to produce proteins and glucose molecules produce sheets of cellulose to form cell walls.

Plant roots absorb mineral salts including nitrate needed for healthy growth, plants need mineral ions including nitrate for amino acids that are then used to form proteins, magnesium which is needed for chlorophyll production.

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Ecosystems

Radiation from the sun is the energy source for most livingg organisms. Green plants capture a small part of the solar energy which reaches them.

The mass of living material (biomass) at each stage in a food chain is less than it was at the previous stage.

The amounts of material contained in the biomass is reduced at each successive stage in a food chain because some materials are lost in the organisms' waste.

The efficiency of food production can be improved by reducing the number of stages in the food chain.

Materials decay because they are broken down.

The carboncycle involves three processes: respiration, photosynthesis and combustion.

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Myst3riousG1rl

part 2 coming soon with more topics! **

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