AQA Biology B1b Revision

• Plants compete for water, nutrients and light
• Some spread seeds over wide area so they don't compete with each other eg, coconuts can float for miles on ocean currents

• New forms of genes mutate from existin genes
• Animals with genes best suited to the environment live and reproduce
• Succesful genes are then passed on to the next generation

Can be caused by

• Changes the the environment
• New predators
• New competitors
• New diseases

• Fossils provide evidence of how much/little organisms have changed
• Difficult to know how life began - no direct evidence
• Theory of Evolution = all species alive today and species that are extinct evolved from simple life forms - 3 billion years ago
• Natural Selection = Evolution

• looking after the environment and improving your quality of life at the same time
• using natural resources wisely
• by; recycling, being energy efficient and using cars less.

• Sampling from differnet areas can be used to estimate population growth
• Environmentalists believe it is important not to build on sites of special scientific interest, so therefore they need to test the land first.

• cuttings - taking a small piece of stem of leaf and growing it on in the right conditions to produce a new plant
• tissue cloning - getting a few cells from a desirable plant to make a big mass of identical cells each which can produce a tiny identical plant
• Asexual reproduction - reproduction which only involves one parent, there is no joining of gametes and the offspring are genetically identical to the parent
• Embryo cloning - splitting cells apart from a developing embryo before they become specilised to produce several identical embryos.

• Fusion cell cloning is a form of asexual reproduction
• Dolly the sheep was created through fusion cell cloning
• in adult cell cloning, a whole cloned animal can result. The nucleus from a cell from an adult animal is transferred to any empty egg cell from another animal, a small electric shock fuses the cells.

• All living things have adaptations which make them live

• plants lose water all the time by evaporation from their leaves
• plants which live in dry places have adaptations which help to reduce water loss. These adaptations may often include reduced surface area of the leaves

• Animals compete for water, food, space, mates and breeding sites
• the most successful ones survive and pass on their genes to the next generation
• some animals have adaptations which make them good competitors, eg, camoflage, poisons or speed

• the population is rapidly increasing as is the standard of living
• more waste is being produced causing pollution
• humans reduce the amount of land available
• raw materials are being used rapidly
• out activity has changed the balance of nature