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What is the difference between allopatric and sympatric speciation?

Allopatric speciation occurs when populations of a species are separated by a physical barrier - this could be a river for animals that cannot swim, for example. Separation of the populations means that ther...
TM
Answered by Tom M. • Biology tutor
65487 Views

What is the structure and function of DNA?

DNA (deoxyribonucleic acid) is a double helix composed of units called nucleotides. Each nucleotide is composed of a single deoxyribose sugar, a phosphate group and one of four nitrogen bases. The 4 bases ar...
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Answered by Sylvia D. • Biology tutor
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Explain why the enthalpy of lattice dissociation of potassium oxide is less endothermic than that of sodium oxide.

Lattice dissociation enthalpy is the enthalpy change when one mole of a gaseous ionic lattice dissociates into isolated gaseous ions. The process is endothermic because energy is required to overcome the ele...
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Answered by Louise J. • Chemistry tutor
27315 Views

How Do I Integrate cos(x) and sin(x) with higher powers?

The answer to this question depends on one thing, whether this power is odd or even. For even powers we use the identity cos(2x) = 2cos^2(x)-1 = 1-2sin^2(x). So for example, the integral of cos^2(x) is found...
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Answered by Ciarán R. • Maths tutor
12231 Views

Why is the pancreas both an endocrine and exocrine gland?

Endocrine organs release their products (usually hormones) directly into the blood. The pancreas contains islets of Langerhans which are made up of alpha and beta cells. Beta cells secrete insulin and alpha ...
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Answered by Rym C. • Biology tutor
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