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Describe the structure of DNA

-DNA is a double-stranded helix-Two polynucleotide strands (that run antiparallel to each other), held together by hydrogen bonding between the complementary base pairs-Each nucleotide consists of deoxyri...

Answered by • Biology tutor

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Why does an enzyme only catalyse one reaction?

Enzymes are proteins, which have a specific 3D tertiary structure, with a specifically shaped active site. The active site can only bind one substrate to...

Answered by Zara S. • Biology tutor

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1.1 Write out the base sequence of the complimentary strand of DNA for the following DNA sequence (ATGGCTACG) (2 marks). 1.2 How many amino acids does the DNA sequence code for? (1 mark)

1.1 Answer: TACCGATGC (T is complimentary to A and C is complimentary to G)1.2 Answer: 3 amino acids (3 DNA bases code for 1 amino acid and there are 9 DNA bases in the sequence (9/3=3))

Answered by Siobhan L. • Biology tutor

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Outline how light intensity affects the rate of photosynthesis, with reference to the Calvin cycle and effects on the concentrations of GP, GALP and RuBP.

Light is needed to provide energy for the light dependent reactions of photosynthesis. A greater light intensity will provide more energy for these reactions to occur. At a low light intensity, the produc...

Answered by Sammy A. • Biology tutor

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What is the difference between the primary and secondary immune responses? (May be asked in the form of how to interpret a commonly used graph on the subject)

In a primary immune response the active immune system must first recognise the pathogen via B-lymphocyte cells with antibodies on their surface that are complementary to the antigens of the invading path...

Answered by • Biology tutor

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