Which two cell structures work together in the process of protein synthesis?*

Prions are proteins that act as an infectious agent. They cause a variety of diseases, including “Mad Cow” disease. Prions cannot produce more prions on their own, but cause the host organism to replicate more prions. Most scientists do not consider prions to be alive. A valid reason for accepting that prions are nonliving things is that*

Which molecule can diffuse from the digestive tract into the human bloodstream without first being digested?*

The nucleus of a cell coordinates processes and activities that take place in the cell. Which two systems perform a similar function in the human body?*

The letters in the diagram below indicate some parts of a cell.

The function of which cell part is most similar to that of the human excretory system?*

In the summer, the arctic fox appears brown because its cells produce a dark pigment. However, in the winter, the arctic fox appears white because the dark pigment is not produced. The color change is most likely due to the effect of*

Many years ago, a scientist grew pea plants that produced wrinkled peas. The peas from these plants produced new plants that also produced wrinkled peas. The scientist concluded that something in the parent plants was being transmitted to the next generation. This discovery is now known as*

The process represented in the diagram below occurs in many cells.

The main function of this process is to*

The Old English Bulldog is extinct. To produce a new English Bulldog, dogs having the desired physical features, but not the aggressive nature of the old bulldogs, were mated. The result was a bulldog that was similar in appearance to the extinct bulldog, but without its fierce nature. Which technique was most likely used to develop this new variety of dog?*

Structure A usually produces*

The placenta forms from the combination of fetal tissue and tissue from structure*

Which factor has the greatest influence on the development of new, inheritable characteristics?*

In 2007, scientists broke open a fossil of a dinosaur bone and found some preserved tissues. Analysis showed that some proteins in these tissues are very similar to proteins found in modern chickens. The conclusion that these dinosaurs are related to modern chickens is based on*

The diagram below represents the bone arrangements in the front limbs of three different species of mammals.

The similarities and differences in these limbs suggest that all three species developed from the same ancestor, but*

For those individuals who have an allergic reaction to cats, a company in Los Angeles promises relief. They offer a new line of cats genetically modified to eliminate or reduce their allergy-causing properties. The development of this new line of cats most likely involved*