According to the geologic time scale, in what era did most types of animals first appear

In which part of the digestive system does a chemical change of the food first occur? mouth esophagus stomach liver

Why did a decrease in bone mass lead to increased calcium levels in the blood?

Which of the following evidence best supports a claim that tryptophan functions as a corepressor? A. Normal expression of trpR causes the trp operon to be transcribed regardless of tryptophan levels. B.

Select all that apply. Select from the following the factors that could cause water to evaporate. oceans solar radiation energy ultraviolet radiation heat

Which biological factors may increase risk for aggressive or illegal behavior? (Select all that apply.) skull shape the personality trait of high conscientiousness body shape exposure to lead or other toxins before birth brain injuries

How are objects placed in space? a. in random pattern b. in a rigid pattern c. in a loose pattern d. in no pattern

Explain the concept of natural selection.

A cell has the following features; a nucleus, mitochondria, ribosomes, a cell wall made of chiton and a cell membrane. What type of cell is described? A) animal B) bacteria C) fungi D) plant

The energy for the water cycle comes from the Sun. a. True b. False

Which tissue type is formed by many cells joining together, each contributing a nucleus? Select one: A. smooth muscle B. cardiac muscle C. dense regular D. skeletal muscle