Feeding Patterns in the Desert Ecosystem

A team of ecologists observed feeding patterns of several populations in the desert. The energy pyramid shown below depicts the feeding patterns the ecologists observed.

Which of the following best explains the difference in the amount of available energy in the trophic levels of the desert ecosystem?

• There is less energy available in the producers because their tissues are less dense than those at higher trophic levels.

• There is more energy available in the second trophic level because less energy is needed for hunting compared to the higher trophic levels.

• There is more available energy in the birds of prey because they have greater muscle mass for storing energy than organisms in lower trophic levels have.

• There is less available energy in the fourth trophic level because of the loss of energy through metabolism in each of the lower trophic levels.

Water is essential for life. Its special properties make water the single most important molecule in plant life. Which of the following properties of water enable it to move from the roots to the leaves of plants?

• Water expands as it freezes.

• Water is an excellent solvent.

• Water exhibits cohesive behavior.

• Water is able to moderate temperatures.

An osmosis investigation was conducted using chicken eggs to represent cells with semipermeable membranes. The mass of each egg was measured to determine how much water diffused into or out of the eggs. The eggs were first soaked in vinegar to dissolve the shell. Each egg was then placed in one of three different solutions for 24 hours. The table below shows the results of the investigation. Based on this experiment, which of the following should be inferred about cells with semipermeable membranes?

• Substances other than water may also cross the cell membrane.

• Substances other than water may block pores in the cell membrane.

• Water enters the cell when placed in environments of high water concentration.

• Water leaves the cell when placed in environments with a low concentration of solutes.

One of the accepted scientific theories describing the origin of life on Earth is known as chemical evolution. According to this theory, which of the following events would need to occur first for life to evolve?

• onset of photosynthesis

• origin of genetic material

• synthesis of organic molecules

• formation of the plasma membrane

Hemophilia is a sex-linked, recessive trait. Which of the following describes the probability of hemophilia in the offspring of a man who does not have hemophilia and a woman who is a heterozygous carrier?

• There is a 100% chance that their sons will have hemophilia.

• There is a 0% chance that their daughters will have hemophilia.

• There is a 25% chance that their sons will have hemophilia.

• There is a 50% chance that their daughters will have hemophilia.

The sodium-potassium ion pump found in some cell membranes is made of which of the following basic structural components?

• amino acids

• fatty acids

• monosaccharides

• nucleotides

What is a primary function of the cell membrane?

• determining genetic traits

• defending against foreign particles

• breaking down proteins for energy

• generating energy from mineral nutrients

Why does the study of cell membranes lead to a better understanding of cell function?

• All cell functions occur in the cell membrane.

• All energy transfers occur at the cell membrane.

• All cell membranes contain the information for making proteins.

• All materials needed for cell functions must pass through the cell membrane.

How does the fossil record provide evidence for evolution?

• It shows the gradual changes in species over time.

• It proves that all species alive today have remained unchanged.

• It demonstrates that species can evolve within a single generation.

• It reveals that all species appeared at the same time.