Variation in traits can be caused by variation in protein molecules within individuals' cells. Protein molecules' structures affect their function and the way they connect to other molecules. Spider silk is made of proteins, and connections between these molecules affect silk flexibility.
Answer:
A
Explanation: sorry i don't know an explanation, its just a name for the layers of gas surrounding the earth
A. Only the movement of matter involves living things
Skeletal muscle.
Why are you still up?
When a habitat is destroyed, the carrying capacity for indigenous plants, animals, and other organisms is reduced so that populations decline, sometimes up to the level of extinction. Habitat loss is perhaps the greatest threat to organisms and biodiversity.Extinction happens when environmental factors or evolutionary problems cause a species to die out. The disappearance of species from Earth is ongoing, and rates have varied over time.