Chlorosis
Chlorosis = when plants aren't producing enough chlorophyll so look pale and yellow --> reduces plant's ability to photosynthesise
Most plants showing chlorosis have the right genes for chlorophyll but its influenced by environmental factors :
Lack of light --> plants turn off chlorophyll production to not waste resources
Mineral deficiencies --> lack of iron or magnesium (iron is cofactor for some enzymes for making chlorophyll and magnesium is used in the chlorophyll molecule)
Virus infections --> viruses interfere with the metabolism of cells, infected tissues no longer support chlorophyll synthesis
Animal body mass
Determined by a mix of genes and environment
Environment --> overfeeding or underfeeding, lack of exercise, presence of disease
Genetic --> pattern of fat deposition can be altered
Creating genetic variation
Created by versions of genes inherited from parents
Individual mixture of alleles influences the characteristics shown
Combination generated by meiosis and random fusion of gametes
Genotype = combination of alleles inherited for characteristic
Phenotype = observable characteristics of organism
Actual characteristics displayed also controlled by environment
Dominant alleles are always expressed
Recessive alleles only expressed if there's two of them
Homozygous = two identical alleles for the characteristic
Hetereozygous = two different alleles for the characteristic (only the dominant one is expressed)
Continuous and discontinuous variation
Continuous = characteristic that can take any value within a range, caused by genetics and environment, controlled by a number of genes --> leaf surface area and animal mass
Discontinuous = characteristic that can only appear in distinct categories, caused by genetics, controlled by one or two genes --> blood group, round and wrinkled pea shape