An experiment was done to look at the effects of iodine supplements on the production of the thyroid hormone thyroxine. Individuals in the study were divided into categorizes based on the dosage of iodine supplemented. The chart below summarizes the data collected. THY1 is the average amount of thyroxine in the group prior to taking the supplement. THY2 is the average amount of thyroxine in the group after three months of taking supplements. 

According to the chart, which dosage of Iodine seems most effective at raising thyroxine levels?

A biologist wanted to do an experiment involving two species of large cat (species A and species B) around a potential new food source.

He isolated the populations of each cat in a location that closely approximated their natural environment, except this potential new food source was the only food source available to them. 

Experiment 1:

When species A was left alone with the new food source, their numbers decreased rapidly until none were left.

Experiment 2:

When species B was left alone with the new food source, their numbers increased and the species flourished.

Experiment 3:

When an equal number of species A and B were placed with the new food source, both species maintained relatively constant numbers.

Which of the following charts could not be used to illustrate the results of experiment 1?

There is a certain species of rabbit that is known to reproduce quickly. 250 of these rabbits were introduced into a new environment, and their population was measured in ten year intervals.

What is the dependent variable in this experiment?

There is a certain species of rabbit that is known to reproduce quickly. 250 of these rabbits were introduced into a new environment, and their population was measured in ten year intervals.

Which of the following is an accurate graphic representation of the data?

Which represents a population in which organisms tend to exhibit phenotypes on the bottem end of the scale?

     Species competition is driven by a variety of factors. Resources such as water, food, sunlight, and suitable habitat are among the top contributors that influence interspecific and intraspecific competition. Interspecific is competition between different species and intraspecific competition is between members of the same species.

     One interesting example of interspecific completion is that of two barnacle species that inhabit intertidal zones. Balanus balanoides inhabits the lower intertidal zone and Chthamalus stellatus inhabits the lower intertidal zone. A researcher attempts to study this phenomenon.

The researcher removes the Balanus species from the lower intertidal zone and observes that the Chthamalus species expands its range to inhabit the lower intertidal zone and the upper intertidal zone. The researcher then removes the Chthamalus species from the upper tidal zone of a different area and observes that the Balanus species does not extend its range. The researcher concludes that competition has allowed each species to exist simultaneously by forming specialized niches that promotes survivorship for each species.

The interaction between Balanus balanoides and Chthamalus stellatus is best described as which of the following choices.

Eukaryotic cells first appeared billions of years ago and were marked by the presence of membrane-bound organelles (organelles with a lipid bilayer surrounding them) similar to the outer and inner membranes of prokaryotes like bacteria. One of these membrane bound organelles is called the mitochondrion, which is responsible for helping generate energy in the form of a nucleotide-sugar molecule called adenosine triphosphate (also known as ATP).

By using only oxygen and glucose (a type of sugar composed of a single molecule) as reactants, the mitochondrion is responsible for generating ATP and water. In order to make ATP, animals must eat food products that contain sugars, such as potatoes, which contain molecules called starches that have many sugar molecules linked together. Once the sugar has been processed in the cell by an enzyme called amylase, it undergoes a process called glycolysis, which breaks down glucose into a molecule called pyruvate and provides 2 ATP molecules in the process.

After glycolysis, the pyruvate molecule is transported to the mitochondrion, carried across its membrane and then enters a process called the Kreb’s cycle, where a net of 34 ATP are produced. However, the process of transporting the pyruvate molecule into the mitochondrion requires 1 ATP. The ATP produced from both glycolysis and the Kreb’s cycle serves to allow the cell to carry out its housekeeping functions.

If a mutation inactivated amylase, how many ATP could be produced from one glucose molecule through the combination of glycolysis and the Kreb's Cycle?

Which of the following represents a normal distribution?

Which represents a population that has more than two modes of phenotypic expression?

Passage I

An endocrinologist is a doctor who studies, diagnoses, and treats patients with hormone imbalances. There are many hormones involved in daily functioning. Two of the most important hormones for digestion are insulin and glucagon. These hormones are secreted by the pancreas. Insulin is released after a meal to help body cells take in sugar and covert it to energy. Glucagon is released when the body needs more energy, such as during exercise, and causes body cells to secrete sugar into the blood. A team of endocrinologists performed the following experiments:

Experiment 1

Five participants were given 15 grams of pure glucose (sugar). The participants had not eaten for four hours prior to the experiment. All five participants were healthy and had no serious medical conditions. A team of endocrinologists monitored the blood sugar and insulin levels of the participants over time. Figure 1 is a graph of the average levels in the five participants.

Experiment 2

Two participants were given 15 grams of pure glucose (sugar). The participants had not eaten for four hours prior to the experiment. One participant was healthy and the other had a hormone disease. Figure 2 is a graph of the blood sugar levels of the participants over time.

Which participant in Figure 2 has an endocrine disease?