Reproduction Flashcards
What does a cell contain?
Most cells contain a nucleus which had genetic material in the form of chromosomes.
In the nucleus it contains 23 pairs of chromosomes. They are always in pairs, one from each parents.
Chromosomes carry genes which control the development of different characteristics like hair and colour.
A gene is a short length of the chromosomes and a long length of the DNA.
The DNA is coiled up to make the arms of the chromosomes.
What is a gene?
Genes are codes in cells that control how we are made. It carries the information that determines our traits, which are features and characteristics passed onto us.
What are the two types of variations?
Generic and environmental
How do different genes cause genetic variation?
All plants and animals contain similar characteristics to there parents. This is because an organisms characteristics is determined by the genes inherited from their parents. The genes are passed on in sex cells called gametes , which the offspring develops from. Most animals get genes from each parent. The combining of genes from two parents causes a genetic variation as no offspring is genetically identical apart from twins.
What is sexual reproduction/ how does it work?
Sexual reproduction is when genetic information is passed on to the offspring from the two organisms when they combine together. The offspring is genetically different to either parents. In sexual reproduction, the mam and dad produce gametes. In the gametes it contains 23 chromosomes which is half the amount in a normal cell. Instead of having two of each chromosome, gametes contain one of each. The egg and sperm cell then fuses together, called fertilisation, and it creates a cell with the full number of chromosomes - half from the mother, half from the father. This is why the offspring inherits features from both parents as its received a mixture of chromosomes from it’s mam and dad. The mixture of genetic material produces variation in the offspring.
What is asexual reproduction/ what is the process?
An ordinary cell can make a new cell by simply dividing in two. The new cell has exactly the same genetic information as the parent cell which is knowing as asexual reproduction. X shaped chromosomes have two identical halves so each chromosome splits to form two identical sets of half chromosomes. A membrane forms around each set and the DNA replicates itself to form two identical cells with complete sets of X shaped chromosomes. In asexual reproduction, there’s only one parent. There is no fusion of gametes, no mixing of chromosomes and no genetic variation between the parent and the offspring. The offspring is genetically identical to the parent - they are clones. That’s how all plants and animals grow and produce replacement cells.
How are characteristics influenced by the environment?
The environment that organisms grow in causes differences between members of the same species. You could have an accident, gain weight or lose a tan and so due to the conditions you live in, it is an environmental variation.
Most characteristics are due to what?
Genes and the environment
What does sexual reproduction need?
Sexual reproduction needs two parents and forms cells that are genetically different to the parents , so theres lots of genetic variation.
What does asexual reproduction need?
Just one parent to make genetically identical cells which are clones, so there’s no genetic variation in the offspring.
What organisms produce offspring using asexual reproduction?
Bacteria and plants.
Advantages of sexual reproduction
Inherits features.
Children.
Natural.
Disadvantages of sexual reproduction
Could be painful.
STD’s.
Advantages of asexual reproduction
Happens faster then sexual reproduction.
It is cheaper and has larger quantities.
Disadvantages of asexual reproduction
Only occurs is plants and animals
