Some scientists argue that no single factor poses a greater threat to the environment than the continued growth of the human population, while others believe the use of resources per person is a more critical factor. What arguments can you think of for or against either proposition?

The largest scale of life, which can be thought of as the interaction of all of Earth’s ecosystems, is called

a. the biome.

b. the ecosphere.

c. the biosphere.

d. the environment zone.

e. the ionosphere.

When population growth increases in proportion to the number of members of a population, __________ growth is said to have occurred.

a. density-dependent

b. density-independent

c. K-selected

d. arithmetical

e. exponential

K-selected species tend to (select all that apply):

a. experience their environments as unstable.

b. have stable populations.

c. have their populations limited by carrying capacity.

d. provide little care to their offspring.

e. be most affected by biological forces.

r-selected species tend to (select all that apply):

a. have their populations limited by reproductive rate.

b. experience their environments as unstable.

c. provide abundant care to their offspring.

d. have populations that are strongly affected by physical forces.

e. face density-dependent pressures on their populations.

The human total fertility rate (select all that apply):

a. is the average number of children born to each family in a population.

b. has been dropping worldwide in recent decades.

c. must be at about 3 for a population to be at replacement level.

d. is generally much lower in less- developed countries.

e. is higher in the United States than in most developed countries.

The number of sperm that can fuse with an oocyte is limited to _______. This is vital in order to make sure that a fertilized egg has a balanced number of _______ from the father and the mother.

With the implantation of the fertilized egg in the wall of the _______, cells in the egg grow into the fetal portion of a network of blood vessels and membranes that support the fetus. This is the _______.

Labor can be defined as regular _______ of uterine _______ that help bring about the birth of the baby.

Sperm begin development in the _______ and continue development and are stored in the convoluted tubules called the _______.

The material that is ejaculated from the penis, _______, is composed of both _______ and fluids secreted by three supporting _______.