GCSE Science B1

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  • Created by: ariana123
  • Created on: 13-04-17 20:08
Where are chromosomes found within a cell?
In the nucleus and genes
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What are alleles?
The different versions of the same gene
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How do genes control the different characteristics we develop?
Each gene is a code for making a certain protein. Proteins are building blocks of cells. Having different versions of proteins means that we end up with different characteristics.
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What do the words 'genotype' and 'phenotype' mean?
An organism's genotype is all of the genes it has. The characteristics that an organism displays are called Phenotype.
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Is a person's weight determined by genes, the environment or both?
Both!
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Name two types of sex cells.
The sperm and egg.
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How many chromosomes are found in sex cells?
23 single chromosomes
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Why do most children look a bit like both their parents but not identical to either?
Half a child's chromosomes have come from each parent. This means that children get some of their alleles from each of their parents.
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What's the difference between homozygous and heterozygous?
Homozygous- you have two alleles the same. Heterozygous- you have two different alleles.
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What sex sells do human males have?
Chromosome: XY
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How does a gene on one of the human sex chromosome cause embryos to develop into males?
The gene that makes an embryo into a male causes a specific protein to be produced.
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Is the allele for cystic fibrosis dominant or recessive?
It is recessive!
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What are the symptoms of cystic fibrosis?
Thick sticky mucus in the air passages, gut and pancreas. Breathing difficulty, chest infections. difficulty in digesting food.
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What are the symptoms of Huntington's disease?
Tremors, clumsiness, memory loss, mood changes, poor concentration.
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During IVF treatment, what is the process of testing embryos to see if they have a genetic disorder called?
Known as Pre-implantation genetic diagnosis.
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Other than testing embryos during IVF, give one other use of genetic testing.
Children and adults can be checked to see if they carry alleles for genetic disorder.
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Describe three issues surrounding genetic testing.
1. Tests carried out during pregnancy aren't 100%. 2. Results of genetic tests may not be 100% accurate. 3. Insurance companies might refuse to give life insurance to people with the 'wrong' alleles.
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Write a definition of the term 'clone'.
Genetically identical organism.
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How can the following reproduce asexually: bacteria, some plants and some animals?
Bacteria: Divides into two. Plants: produce horizontal stems called runners that move out from the base of the plant and form new clones or produce underground fleshy structure called bulbs. Animals:Female greenfly don't need to mate, they lay eggs.
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How are identical twins formed?
The embryo splits into two and two separate embryo begins to develop.
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What are stem cells?
They are unspecialised cells.
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What are the difference between the two main types of stem cells?
Embryonic: Found in the early embryos and are removed from it, before the embryos are destroyed. Adult: Found in adult animals and are involved in maintaining and repairing old and damaged tissues and can specialise into many cells.
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Describe one way that stem cells could be used to treat an illness.
Some blood disease can be treated by bone marrow transplant- Adult stem cells.
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Other cards in this set

Card 2

Front

What are alleles?

Back

The different versions of the same gene

Card 3

Front

How do genes control the different characteristics we develop?

Back

Preview of the front of card 3

Card 4

Front

What do the words 'genotype' and 'phenotype' mean?

Back

Preview of the front of card 4

Card 5

Front

Is a person's weight determined by genes, the environment or both?

Back

Preview of the front of card 5
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