The answer is b)
The niche is the job the animal does in it's habitat to contribute to the habitat.
Tumor suppressor genes encode for proteins that inhibit or slow the progression of the cell cycle through a specific stage.they also encode for check point control proteins that arrests the cell cycle if the DNA is damaged or the chromosomes are abnormal. Mutation in the tumor suppressor genes that cause a loss or decreased function would lead to uncontrolled cell cycle leading to abnormal proliferation and the cell may become cancerous.
The effect of a neurotransmitter is based on the properties of the receptor more than the neurotransmitter.
Organism
population
community
ecosystem
