Topic 6 - Inheritance, Variation and Evolution (1) Flashcards
REPRODUCTION:
What does sexual reproduction produce?
genetically different offspring
REPRODUCTION:
What happens in sexual reproduction?
- genetic information from 2 organisms (father and mother) are combined to produce offspring that are genetically different to either parent
- the mother and father produce gametes by meiosis e.g. egg and sperm cells in animala
REPRODUCTION:
What is the process in which the mother and father prosuce gametes?
meiosis
REPRODUCTION:
In humans, how many chromosomes does each gamete contain?
Compare this to normal cells
23 - half the number of chromosomes in a normal cell
- instead of having two of each chromosome, a gamete just has one of each
REPRODUCTION:
What is the name of the process where the egg and sperm fuse together?
fertilisation
REPRODUCTION:
What happens in fertilisation?
the egg (from the mother) and the sperm cell (from the father) fuse together
this forms a cell with the full number of chromosomes - half from the mother and half from the father
(as each gamete only has 23 chromosomes)
REPRODUCTION:
What are the main characteristics of sexual reproduction?
- involves the fusion of male and female gametes
- there are 2 parents
- so the offspring contain a mixture of their parent’s genes
REPRODUCTION:
Why do offspring from sexual reproduction inherit characteristics from both parents?
- its recieved a mixture of chromosomes from its mum and dad
- its the chromosomes that determine the characteristic you have
REPRODUCTION:
In sexual reproduction, what does the mixture of genetic information produce?
variation in the offspring
REPRODUCTION:
When flowering plants reproduce sexually, what are their gametes?
- egg cells (female)
- pollen (male)
REPRODUCTION:
What does asexual reproduction produce?
genetically identical offspring
REPRODUCTION:
What type of reproduction only involves one parent and what does this mean for the offspring?
- asexual reproduction
- the offspring are genetically identical to their one parent
REPRODUCTION:
What process happens in asexual reproducton?
- asexual production only involves mitosis (an ordinary cell makes a new cell by dividing in 2)
REPRODUCTION:
Asexual reproduction: when the new cell had exactly the same genetic information (genes) as the parent cell, what is it called?
a clone
REPRODUCTION:
What are the main characteristics of asexual reproduction?
- only one parent
- no fusion of gametes
- no mixing of chromosomes
- no genetic variation between parent and offspring
- the offsping are genetically identical to the parent (they are clones)
REPRODUCTION:
What types of organisms reproduce asexually?
- bacteria
- some plants
- some animals
MEIOSIS:
What does meiosis produce?
gametes
MEIOSIS:
Why do gametes only contain one copy of each chromosome?
so that when gamete fusion takes place, the zygote has the right amount of chromosomes (two copies of each)
MEIOSIS:
How are gametes made to only have half the number of original chromosomes?
cells divide by meiosis
MEIOSIS:
How many cell divisions does meiosis involve?
2
MEIOSIS:
Where does meiosis happen in humans?
it only happens in the reproductive organs (ovaries in females and the testes in males)
MEIOSIS:
What happens after two gametes have fused during fertilisation?
- the resulting new cell divides by mitosis to make a copy of itself
- mitosis repeates many times to produce lots of new cells in an embryo
- these cells then start to differentiate into different types of specialised cell that make up a whole organism
