B1 - Flashcards

chelseal_obrien
Flashcards by chelseal_obrien, updated more than 1 year ago
chelseal_obrien
Created by chelseal_obrien about 6 years ago
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Flashcards on B1 - Flashcards, created by chelseal_obrien on 02/16/2015.

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B1 Revsion Cards - Evolution Darwin’s theory of evolution by natural selection states that all species of living things have evolved from simple life forms that first developed more than three billion years ago.
Natural Selection - 'Survival of the fittest' The theory of evolution by natural selection was only gradually accepted because: -The theory challenged the idea that God made all the animals and plants that live on Earth. -There was insufficient evidence at the time the theory was published to convince many scientists.
Lamarck Thoery- Was based on the idea that if a characteristic was used a lot by an organism then it would become more developed during its a lifetime. Evolution can occur due to Mutations- A mutation is a change in organism's DNA. Occasionally they can produce a useful characteristic which may give the organsim a better chance of suriving and reproducing.
Variation- Is where the same speicies have differences in characteristics. These are genetic and environmental. B1 Revision Cards - Reproduction
Sexual Reproduction – The joining (fusion) of male and female gametes. The mixture of the genetic information from two parents leads to variety in the offspring. Asexual Reproduction – No fusion of gametes and only one individual is needed as the parent. There is no mixing of genetic information and so no genetic variation in the offspring. These genetically identical individuals are known as clones.
Plants can be cloned by: -Cuttings are taken from a good parent plants, and then planted to produce gentically identical copies. - Tissue Culture- A few plant cells are put into a growth medium with horones and they grow into new plants. Animal Clones using Embryo Transplants- Splitting apart cells from a developing animal embryo before they become specialised, then transplanting the identical embryos into host mothers. Adult Cell Cloning- Involves taking an unfertillised egg and removing its nucleus. The egg is then given an electric shock to start cell division. Then planted into an adult female ( Surrogate mother)
Genetic Engineering - The use of enzymes to copy a useful gene from one organism's chromosomes into the cells of an other. Genes can be transferred into Animals and Plants from genetic engineering. e.g GM Crops have had their genes modified to make them resistant to insects and herbicides.
B1 Revision Cards- Decay Process Living things remove materials from the environment for growth and other processes. These materials are returned to the environment either in waste materials or when living things die and decay.
Materials decay because they are broken down ( digested) by microorganisms. Microorganisms are more active and digest materials faster in warm, moist, areobic conditions. The decay process releases substances into the environment which help plants grow.
B1 Revision Cards - Energy in Biomass Biomass - The amount of living material. At each stage in a food chain there is less than the previous stage.
Radiation from the sun is the source of energy for most living organisms. The transfer of light to chemical energy occurs in photosynthesis. This energy is then stored in cells. The amount of biomass is reduced in each stage due to: - Energy is lost in the organisms waste matieral. -Energy being transferred to the surroudings.
B1 Revision Cards- Adaptations To survive and reproduce, organisms require a supply of materials from their surroundings and from other living organisms. Plants often compete for light, water and nutrients from the soil. Animals often compete for food, mates and territory.
Animals and plants are also adapted for survival in the conditions in which they live. Animals and Plants in the desert are adapted to keep cool and save water. Whereas Animals and plants in the arctic are adapted to reduce heat loss.
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