could someone explain cloning, natural selection, asexual and sexual reproduction please?

  • 0 votes

i am revising for my unit 1 biology higher exam next week. my exam board is aqa. i am struggling with the whole cloning, sexual/ asexual reproduction and natural selection topics, please can someone help and explain? thank you so much!

Posted Wed 6th June, 2012 @ 23:13 by lucy presley

7 Answers

  • 4 votes

Cloning: Cloning is what they did to Dolly the sheep, which is an example of this. They take the egg cell out of the mother and remove the genetic material from it, meaning that no genetic material is being passed on from the mother. An adult body cell is taken from the animal in which they want to clone and the nucleus is taken out. This nucleus is placed into the empty egg cell, and left to divide and grow like a normal cell, it contains all the genetic material from the father so will be a identical 'clone' of this animal. The cell is placed into another animals womb to grow and develop until it develops fully and can be born.  (It is a very controversial topic as many believe that it is wrong. For example dolly the sheep was cloned from an older sheep so although when she was born she was born in the younger body but had all the physical atributes of an older sheep including all the health problems that the older sheep has. This caused many problems in society as it caused unnecassary harm to a sheep.) 

Sexual reproduction: sexual reproduction is when to mammals have sexual intercourse and the sperm meets the egg. Genetic information is taken from both parents, 23 chromosomes from the mother and 23 chromosomes from the father, meaning that the foetus and the baby will have genetic information from both parents.

Asexual reproduction: this is when the mother cell divides into too and reproduces itself this way. The new 'product' will be identical to the mother because of the only place the genetic material has come from is her. Strawberrys and potatoes are both plants that do asexual reproduction. 

Natural Selection: This is when small mutations occur when a mother gives birth to her young. These mutations enable the young to sometimes be better equipped to survive in the surrounding environment, this means that this young is more likely to survive than the rest, hence the term 'natural selection' as the young are selected naturally with these small differences. 

Answered Thu 7th June, 2012 @ 15:20 by Char Lee
Edited by Char Lee on Thu 7th June, 2012 @ 15:22
  • 1 vote

Asexual reproduction = is reproduction where there is only one parent involved. An example of this is mitosis. Mitosis is the cloning of body cells which is very helpful as it is used in repair and growth of cells.

Sexual reproduction = is the fusion of haploids (half) between male n female gametes which form a diploid cell (normal amout of chromosomes). The production of these gametes is by meiosis n this can give rise to variation etc .

If u cant learn both a little trick is to learn just one and the opposite will be for the other one!!

I will give a more extended answer once i gathered more information. Sorry for the short answer but hope it helps!!!

Answered Wed 6th June, 2012 @ 23:41 by Braniac
  • 1 vote

haha thankyou ** 

Answered Fri 8th June, 2012 @ 20:04 by Char Lee
  • 0 votes

char lee wot an amazin answer . I salute u ;D **

Answered Thu 7th June, 2012 @ 17:09 by Braniac
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thank you

Answered Tue 5th March, 2013 @ 22:15 by sabrina
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Embryo transplants

A developing embryo is removed from a pregnant animal at an early stage, before the embryo's cells have had time to become specialised. The cells are separated, grown for a while in a laboratory, and then transplanted into host mothers.

When the offspring are born, they are identical to each other. They are not identical to their host mothers, because they contain different genetic information (the offsprings' DNA comes from the original pregnant animal and the father).

Fusion cell cloning

Fusion cell cloning involves replacing the nucleus of an unfertilised egg with the nucleus from a different cell. The replacement nucleus can come from an embryo, but if it comes from an adult cell, it is called adult cell cloning.

  1. An egg cell was removed from the ovary of an adult female sheep, and its nucleus removed.
  2. The nucleus from an udder cell of a donor sheep was inserted into the empty egg cell.
  3. The fused cell then began to develop normally, using genetic information from the donated DNA.
  4. Before the dividing cells became specialised, the embryo was implanted into the uterus of a foster mother sheep. The result was Dolly, genetically identical to the donor sheep.

(http://www.bbc.co.uk/schools/gcsebitesize/science/images/cloning.gif)

The cloning process of 'Dolly the sheep'

BBC bitesize really helps

Answered Tue 5th March, 2013 @ 22:28 by Meriyam Younis
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char lee's answer for natural reproduction isnt correct, it is basically survibal of animals because they have a genetic or physical benefit such as light or white fur in a snowy region

Answered Sun 10th March, 2013 @ 14:55 by Nathan