B2 Summaries
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- Created on: 14-12-16 21:05
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- B2 Summaries
- Cells, tissues and organs
- The parts of cells are called organelle, each has an important part to play in the function of the cell.
- Plant, animal and microbial cells have many similarities and some differences.
- In animals and plants, cells are grouped into tissues. Organs are made up of different tissues working together to carry out a function.
- Different types of cells have different structures which enable them to carry out their specific functions. They are specialised.
- Oxygen and other dissolved substances move into and out of cells by diffusion.
- Plants and the environment
- Chlorophyll in plant cells absorbs energy from sunlight. This energy is used to convert carbon dioxide and water to glucose and oxygen in a reaction called photo-synthesis.
- Glucose is used to supply energy; to make cellulose for cell walls; to make storage substances like starch and fats; and to make protein to build new cells and enzymes.
- Quantitive data about the distribution of organisms can be collected using quadrats and transects.
- Limiting factors, including light, temperature and carbon dioxide concentration,affect the rate of photo-synthesis.
- The distribution of different species of organism in the environment is affected by physical factors. These include temperature, nutrients, light, water, oxygen and carbon dioxide.
- Proteins and respiration
- All living organisms release energy from glucose by respiration.
- In anaerobic respiration, a small amount of energy is released from glucose without using oxygen.
- Protein molecules are long chains of amino acids. Hormones, antibodies and enzymes are all proteins.
- The rate at which enzymes work is affected by temperature and pH.
- In aerobic respiration, energy is released when glucose is combined with oxygen. During exercise, when muscles are using a lot of energy, heart rate and breathing rate increase to provide muscles with extra oxygen.
- Enzymes are biological catalysts which control all metabolic reactions, including digestion. They are also used in the home and in industry.
- Cell division, inheritance and speciation
- Fossils provide evidence about some of the species that lived long ago.
- Genetic diagrams can be used to predict the probable character-istics of the offspring of the two parents.
- Cells normally divide by mitosis, which results in two genetically identical daughter cells. To produce gametes, cells divide by meiosis, which produces genetically different cells, each with half the normal number of chromosomes
- New species can arise if two populations of a species become separated. Natural selection may result in them becoming so different that they can no longer interbreed.
- Clones can be created artificially by taking cuttings and carrying out tissue culture, embryo transplants and adult cell cloning.
- Genes are passed from one generation to the next. A gene controlling a particular characteristic may have different forms, called alleles. Some diseases, such as cystic fibrosis which can be inherited.
- Cells, tissues and organs
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