4.Explain the major factors that threaten biodiversity. What is the most effective way to slow down the decrease in marine biodiversity? Why?
3.Please define a "keystone species" and present an example to show how a keystone species affects the biodiversity of a community.
2.Please describe an action potential, including the triggering and changes in membrane potential and ionic fluxes across the membrane. If the amplitude of an action potential is lower than normal, what can be going wrong?
20.A biological species is defined as a group of organisms that (A)are physically similar (B)are genetically similar (C) share a common ancestor (D)live together (E)can inbreed in nature and produce fertile offspring
19.During which phase of mitosis does the nuclear envelope re-form and the nucleoli reappear? (A)anaphase (B)metaphase (C) prophase (D)interphase (E)telophase
18.Oxygen crosses a plasma membrane by (A)osmosis (B)phagocytosis (C) active transport (D)pinocytosis (E)passive transport