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What is an allele? What are dominant and recessive alleles?

The nucleus of a cell contains DNA molecules, which code for proteins. In humans, DNA is arranged into 46 linear, double-stranded molecules called chromosomes. Chromosomes of similar length are paired up – f...
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Answered by Christina T. • Biology tutor
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What's the difference between genotype and phenotype?

The genotype of an organism is the alleles it has. while the phenotype is the characteristics the alleles produce. For examples the alleles for hair colour could be BB for brown hair and Bb for blonde hair, ...
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Answered by Lauren G. • Biology tutor
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What are gene mutations?

A mutation is any change to the base sequence of DNA. The different types of mutations that can occur include: Subsitution - this is where one base is swapped for another Deletion - one or more bases are rem...
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Answered by Lauren G. • Biology tutor
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How are the human lungs specialised for gas exchange?

Gas exchange is when oxygen is transferred from the air in the lungs to the blood and carbon dioxide is transferred from the blood to the air in the lungs. It occurs in the alveoli of the lungs.The lungs hav...
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Answered by Anna D. • Biology tutor
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What is endosymbiosis and how does it relate to mitochondria?

Endosymbiosis is where two organisms live together, one inside the other: endo=in, sym=together and biosis=living. It is believed that mitochondria originated as eubacteria that were intracellular parasites ...
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Answered by Aidan H. • Biology tutor
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