Random
which disease is caused by a dominant allele and not a recessive allele
Huntington's chorea
What is Cystic Fibrosis
Its a disorder of the cell membranes caused by a defective gene. The result of the defective gene is that the body produces a lot of thick sticky mucus in the lungs
Define Gamete
Is either the sperm cell or egg cell
Another name for selective breeding
Artificial selection
Define Mitosis
the process of cell division where one cell splits into two identical cells.
What causes differences in twins
by slight differences in their environment throughout their lives.
Do both parents have to have the Defective gene for Cystic Fibrosis
Both parents must have the defective gene for the disorder to be passed on although both may be carriers.
Define Dominant and Recessive
A dominant allele dominates a recessive allele
What are the best features for farm animals selective breeding
Maximum yield of meat, milk, grain
Good health and disease resistance
First step of Mitosis
DNA all spread out in long strings
What is the Y chromosome
Y chromosome is dominant and causes male characteristics
Fifth step of Mitosis
The threads unwind into long strands of DNA and the whole process then starts over again
Define Zygote
is the delightful name given to each newly formed human life, just after the gametes fuse together at fertilisation
What does selective breeding reduce
the number of alleles in a population because the farmer keeps breeding from the best animals and plants, same ones all the time
Second step of Mitosis
DNA forms into chromosomes. Remember, the double arms are duplicates of each other
What is the percentage of the offspring being a boy or girl
50:50
Sixth step of Mitosis
That single chromosome threads have now duplicated themselves
Define Allele
Another name for gene, you have different versions of a gene, H and h they you have to call them alleles instead of genes.
Give one example where selective breeding is very useful in farming
Selective breeding beef cattle to get the best beef
Third step of Mitosis
Chromosomes line up along centre and then the cell fibres pull them apart.
What does the combination of XX cause
This combination allows female characteristics to develop
Define Parental F1 and F2 Generations
The two originals that you cross are the parental generation, their kids are the F1 generation and the grandchildren are the F2 generation
What is the basic process involved in selective breeding:
From your existing stock select the ones which have the best characteristics
Breed them with each other
Select the best of the offspring, and combine them with the best that you already have and breed again
Continue this process over several generations to develop the desired traits.
Fourth step of Mitosis
Membranes form around the two sets of chromosome threads. These become the nuclei of the two daughter cells.