Biology by Bradford
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The subtopic in the middle and four tasks round it: label a diagram, complete a table and fill 8 gaps. Every box rests on a learning objective of the topic in the AP Biology course and exam description. Type into the blanks and check them, or print it on A4, Letter or A3 with an answer key.
| Example | Environmental factor | Effect on phenotype |
|---|---|---|
| soil pH | flowers pink in basic soil, blue in acidic soil | |
| Himalayan rabbit | temperature | the enzyme for dark fur works only in the ears, nose and paws |
| Alligators and many turtles | incubation temperature | decides whether eggs become male or female |
| Human height | nutrition | a well-fed child grows taller than genes alone would give |
Environmental signals act by changing which genes are expressed or how active a protein is. In the Himalayan rabbit, one enzyme in the pigment pathway is -sensitive and denatures where the skin is warm. Because genes and the environment act together, a population of identical genotypes shows phenotypic variation, but only the genetic part is inherited.
An organism's phenotype comes from its genotype and the environment it develops in. A plant grown in and a plant of identical genotype grown in deep shade look different. Identical twins share a genotype, but fingerprints, weight and risk of disease still differ, and differences grow with age as their environments diverge.
| Example | Environmental factor | Effect on phenotype |
|---|---|---|
| Hydrangea | soil pH | flowers pink in basic soil, blue in acidic soil |
| Himalayan rabbit | temperature | the enzyme for dark fur works only in the cool ears, nose and paws |
| Alligators and many turtles | incubation temperature | decides whether eggs become male or female |
| Human height | nutrition | a well-fed child grows taller than genes alone would give |
An organism's phenotype comes from its genotype and the environment it develops in. A plant grown in sun and a plant of identical genotype grown in deep shade look different. Identical twins share a genotype, but fingerprints, weight and risk of disease still differ, and differences grow with age as their environments diverge.
Environmental signals act by changing which genes are expressed or how active a protein is. In the Himalayan rabbit, one enzyme in the pigment pathway is temperature-sensitive and denatures where the skin is warm. Because genes and the environment act together, a population of identical genotypes shows phenotypic variation, but only the genetic part is inherited.