Unit 1B - Environmnet and Evolution Flashcards

Question

What causes environmental variation?

Answer 1

The environment

Answer 2

Most cells contain a nucleus The nucleus contains 23 pairs of chromosomes The chromosomes carry genes Genes control the development of different characteristics DNA makes up the genes

Answer 3

Sexual reproduction | Asexual reproduction

Answer 4

``` Two organisms (male and female) are required The sex gametes from each individual fuse together to form a cell with 23 pairs of chromosomes half from the mother half from the father The mixture of the genetic material produces variation ```

Answer 5

On,y one parent is involved there is no fusion of gametes, no mixing of gametes and no genetic variation between the parent and the offspring they are genetically identical It works by mitosis

Answer 6

They can be cloned from cuttings and tissue culture

Answer 7

Gardeners take cuttings from a good parent plant and then plant them to produce identical copies. They are kept in moist and warm conditions until they are ready to be planted by covering them in a clear plastic bag Plant hormones are used to stimulate growth They are produced quickly and cheaply

Answer 8

Plant tissue is removed from the parent plant The tissue is placed in sterile agar jelly with the correct conditions needed to maximise plant growth The cells divide and grow rapidly until they develop stems and roots where they are planted in potting trays and develop into clone plants These plants can be made very quickly with little space but cost more money

Answer 9

Sperm is taken from a prize bulb and the egg from a prize cow They are fertilised outside the body of the cow and once an embryo it is formed is split many times into small cluster of cells before any of the cells become specialised These cells then develop into identical embryos which are implanted into surrogate mothers and are born as clones of each other

Answer 10

The nucleus from a female egg cell is removed and is replaced with the nucleus from an adult body cell of the animal that is being cloned The cell is then given an electric shock to get it to to start dividing and to form an embryo The embryo is then implanted into a surrogate mother and a clone is born

Answer 11

Cloning means there is a reduced gene pool which means that a population could easily be wiped out by a disease as none of them will be immune to it as they are all the same People worry that humans might be cloned Cloned animals may not be a healthy, dolly the sheep had arthritis

Answer 12

Studying clones can help develop understanding of embryos, ageing and age related disorders Can help preserve endangered species More food from prize cows

Answer 13

An enzyme is used to cut a useful game from an organism Another enzyme is then used to cut another organisms chromosome and insert the gene into it This is useful for the production of insulin as it is inserted in bacteria and they reproduce rapidly so more human insulin is produced

Answer 14

Crops that have had their genes altered to make them resistant to viruses, insects or herbicides for example

Answer 15

This is where genetic disorders are countered by inserting working genes into suffers eg. People with cystic fibrosis

Answer 16

Can be used to treat disease, more efficient food production etc. People are worried about the long term effects and the chance of unplanned problems occurring that are then passed onto future generations

Answer 17

Some people say they will affect the number of weeds and flowers and will reduce farmland biodiversity Worries about being allergic to the crops and that they're not safe to eat Possibility of transplanted genes getting out into the environment eg. Resistance to herbicides could be picked up by a weed species creating a super weed However they can increase the yield of food They can have nutrients added that people in developing countries are lacking They are already being grown elsewhere in the world and there have been no problems

Answer 18

More than 3 billion years ago, life on Earth began as simple organisms from which all the more complex organisms evolved.

Answer 19

Charles Darwin Individuals in species show variation due to differences in their genes Individuals that have characteristics that make them better adapted have a higher chance of surviving for longer and therefore reproducing more The genes are then likely to be passed onto the next generation, increasing the proportion of the population that has the gene this repeats until most of the species possesses the gene

Answer 20

It went against religious beliefs Darwin could not provide a good explanation for why these new characteristics appeared There was not enough evidence to convince many scientists

Answer 21

Lamark came up with the theory that acquired characteristics would be passed on to the next generation for example a rabbit that use its legs to run a lot would produce offspring that had longer legs

Answer 22

Lamarks hypothesis was rejected as scientists could prove it was incorrect however there is a lot of evidence to support Darwin's theory therefore it is widely excepted today