Biology
Explain the following terms:
(i) Allele
(ii) Diffusion
(iii) Photolysis
(iv) Phenotype
(v) Population density
Genetics
ICSE 2020
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Answer
(i) Alternative forms of a gene, occupying the same position on homologous chromosomes and depicting different forms of the same character are called alleles.
(ii) Diffusion is the free movement of molecules of a substance from the region of their higher concentration to the region of their lower concentration when the two are in direct contact.
(iii) Photolysis is the splitting of water molecules into hydrogen ions and oxygen in the presence of light.
(iv) The observable characteristics which are genetically controlled are called as phenotype.
(v) Population density is the number of individuals per square kilometre (km2) at any given time.
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