B2.5 Flashcards

Beschreibung

GCSE Biology (Unit 2) Karteikarten am B2.5 Flashcards, erstellt von Mel Hughes am 31/08/2016.
Mel Hughes
Karteikarten von Mel Hughes, aktualisiert more than 1 year ago
Mel Hughes
Erstellt von Mel Hughes vor etwa 8 Jahre
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Zusammenfassung der Ressource

Frage Antworten
Which type of cell division produces two identical cels from the original cell? Mitosis
What type of cells are produced by meiosis? Sex cells or gametes, eggs and sperm
Explain how four gametes are formed from one cell There are two sets of cell division. A body cell divides into two each divides again
Where are stem cells found in adult humans? Bone marrow
Which scientist worked out how characteristics are inherited? Mendel
What does a gene code for? The order of amino acids in a protein
Which sex chromosomes are found in human males? X and Y
What is meant by the term 'phenotype'? This is a description of the physical characteristics
Name a genetic disorder which is controlled by a dominant allele Polydactyly
What are the chances of a child having cystic fibrosis if one parent has the disorder and the other parent is heterozygous? 50%, as one parent (cc) has to pass on the allele, the other parent (Cc) has a 50% risk of passing it on; the child is either Cc or cc
What is embryo screening? Tests are carried out on the embryo to diagnose possible disorders
Why do cells divide by mitosis? To produce identical cells for growth and to replace cells
How many chromosomes does a human have in each body cell? 23 pairs (or 46)
Which type of cell division produces sex cells? Meiosis
What molecule are genes made of cells? DNA
What are 'alleles'? Different forms of a gene
Why does sexual reproduction result in variation? The genetic material from two parents is brought together when the sperm and egg nuclei fuse
Explain why offspring produced by asexual reproduction are genetically identical They are produced by mitosis. Cells from one parent divide to produce identical cells
What is meant by the term 'genotype'? The types of genes present in the cells
What do we mean by a 'heterozygous' individual? The individual has one dominant and one recessive allele for a condition
What are the chances of a child having polydactyly if one parent is heterozygous and the other parent is homozygous recessive? 50%, as the dominant gene controls the condition; a child has a 50:50 chance of inheriting the allele from the heterozygous parent
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