Crayfish are freshwater crustaceans. They breathe through feather-like gills and are found in water that does not freeze to the bottom. They are mostly found in brooks and streams where there is fresh water running. Most crayfish cannot tolerate polluted water. Crayfish feed on living and dead animals and plants. Dennie wanted to see if crayfish preferred one kind of food over another. He gave one group of crayfish plants, both living and dead, to eat. He gave the other group insects, living and dead, to eat. What is the independent variable in Dennie's experiment?

A) type of food
B) weight of crayfish
C) type of water used
D) age of the crayfish

Ry was studying two populations of the same species of lizards. one population lived on an island and the other lived on the mainland. both populations were affected by a hurricane that hit the island and the mainland with equal force. a year later, henry was testing the gene frequency and saw a decrease in genetic variation in the island species, but not in the mainland species. which best describes a conclusion he might have reached? gene flow greatly affects small populations, but large populations can recover. genetic drift greatly affects small populations, but large populations can recover. gene flow greatly affects large populations, but small populations can recover. genetic drift greatly affects large populations, but small populations can recover.

Anurse is in the dining room and overhears a new nurse tell a client with body dysmorphic disorder that she's much too thin and must eat more before she can go home. the client bursts into tears and runs out of the dining room. what is the best way for the nurse to address this situation?

Imagine a self-reactive t cell that has not undergone clonal deletion in the thymus (that is to say, it has escaped central tolerance). if it encounters self antigen in the absence of an infection or inflammation, what will happen to this self-reactive t cell? (select two answers) (a) the t cell undergoes clonal expansion. (b) the t cell gains effector functions. (c) the t cell undergoes apoptosis. (d) the t cell becomes activated. (e) the t cell becomes anergic.