bio regent

4 Identical twins were separated at birth and raised by two different families. Years later, one twin was a physically fi t member of the cross-country team, and the other twin was overweight with slightly higher-than-normal blood pressure. The differences in these twins could be explained by the fact that

) the environment can influence the expression of genes

In a DNA molecule, if 38% of the molecular bases are C (cytosine), what percent of the bases are T (thymine)?

12

Which number would indicate the most recent common ancestor of the hyrax, elephant, and manatee on the section of this mammalian evolutionary tree?

2

The messenger RNA sequence that is most likely to produce a functional protein is

AUG-UAU-CGA-GGA-GUU-GCG-CUC-UGA

Dodder plants consist of tangled masses of yellow, leafless vines and contain few chloroplasts. The vines twist around and grow into the stems of other plants and absorb water and nutrients from them. Which statement best describes this relationship?

Dodder plants are parasitic, relying on host organisms for resources.

Which statement best describes a characteristic of the carrying capacity of an ecosystem?

It is limited by the habitat's available energy and nutrients.

Using microscopes he constructed in the 1600s, Antonie van Leeuwenhoek discovered a new microscopic world. His discoveries paved the way for the development of the microscopes used today and for many important biological breakthroughs. Which statement best describes van Leeuwenhoek's work?

Knowledge gained by his work has led to the improvement and development of modern scientifi c concepts

How does the ability to produce 3000 to 6500 eggs benefi t the species?

More offspring are likely to survive and reproduce.

The messenger RNA sequence that codes for the amino acid chain TYR-ARG-GLY-VAL-ALA-LEU is

UAU-CGA-GGA-GUU-GCG-CUC

Orcas are endangered whales. Only about 80 individuals remain off the coast of Washington State. Salmon are a source of food for orcas. Some individuals are proposing that four dams in Washington State be removed so that habitat areas for salmon will be increased. Those opposed to the dam removals say that the dams provide low-cost hydroelectric power and positively influence the local economy

a decision where benefits and risks have to be weighed

An increased demand for soybeans has led to an increase in converting native forests and grasslands to fields for growing soybeans. One negative consequence of this environmental change has been

a decrease in suitable habitats for wildlife

Students did an experiment comparing the activity of four different enzymes, A, B, C, and D. The results are represented in the graph below. A valid conclusion based on the information in the graph is that

a difference in the pH of an environment changes enzyme activity

Base your answers to questions 33 and 34 on the information below and on your knowledge of biology. Anabolic Steroids Anabolic steroids are hormones that affect muscle growth. Many athletes take synthetic anabolic steroids, in hopes of developing larger muscles so they can perform better at their sport. These hormones can act like the hormone testosterone. When men take an excess of anabolic steroids, they can have an increase in feminine features. This is due to the fact that the excess of these chemicals signals the male body to stop producing testosterone. 33 This signal in the male body to stop producing testosterone is an example of

a feedback mechanism

There are over 2000 kinds of edible insects in the world, and they are becoming an increasingly popular source of protein. One cup of cricket fl our contains over 28 grams of protein. The building blocks of the protein in cricket fl our are

amino acids

One reason why anabolic steroids can imitate the hormone testosterone is because

anabolic steroids and testosterone both interact with the same cell receptors

Gene mutations can be caused by many things. These mutations are biologically important because they

can result in a new variety of gene combinations in the species

It may be harmful when people compete to see who can hold their breath the longest under water. Without oxygen, brain cells

cannot make enough ATP

In the 1660s, Flemish physician Jan van Helmont grew a small willow tree in a pot of soil. He added only water to the pot. At the end of fi ve years, he found that the tree had gained 75 kilograms, but there was very little change in the mass of the soil. Van Helmont concluded that the plant gained weight directly from the water. We now know that this conclusion is only partially correct because, in addition to water, photosynthesis also requires

carbon dioxide from the atmosphere

Some viruses attack cells by attaching to their outer covering, entering, and taking over their genetic "machinery." Viruses are able to invade cells after fi rst attaching to their

cell membrane

8 The diagram below represents a food web in a pond ecosystem. Two carnivores in the food web are

crabs and crayfish

After 20 minutes, the section of paper towel connecting the two beakers had turned color. The towel most likely turned green as a result of the

diffusion of the blue- and yellow-dyed water across the towel

The diagram below represents changes that take place within the human body. Instability in internal conditions Stability Stimulus Response Stability

dynamic equilibrium

The Venus flytrap is a plant that has a unique system by which it traps and breaks down its prey. Unsuspecting insects land on the leaf and touch tiny hairs located on the leaf, triggering the leaf to close around the prey

enzyme molecules

The reason for the dramatic decline in the number of measles cases from the 1960s to 2010 in the United States was because the vaccine

exposed many people to a weakened form of the measles virus, making them immune

The evidence that would be most convincing in determining that the plant pieces found in the suspect's hood matched the plants outside the home that was robbed would be if they both had the same

gene sequence

Traits are passed from parents to offspring. These traits are determined by

genes, located on chromosomes, found in the nucleus

Scientists have incorporated a barley gene into a type of rice and produced rice plants that have much lower methane emissions. It is most likely that the scientists incorporated the barley gene into the rice, producing a new variety, using the process of

genetic engineering

An experiment is carried out to determine how different pH values of soil will affect the growth of tomato plants. In this experiment, the dependent variable could be the

height of the tomato plants

Euglena are unique single-celled organisms. Depending on the physical conditions present in their aquatic environment, Euglena can act as either producers or consumers. Euglena will most likely act as consumers when placed in an environment that has

little or no light present

A small lizard spends the morning hours lying in the sunlight until its body temperature rises. Later on in the day, the lizard rests in a shady area until its body temperature cools. This type of behavior is important to

maintain homeostasis

In which cell structure is energy extracted from nutrients?

mitochondrion

3 Protein synthesis is accomplished primarily by the interaction of which two cell structures?

nuclei and ribosomes

Organisms that live on land rarely compete for

oxygen

In order to compare the composition of the pigments on the suspect's jeans to the pigments of the plants at the home, the forensic scientist should use

paper chromatography

Maintaining a rich variety of genetic material that may lead to discoveries useful to humans can be ensured by

preserving biodiversity

Many bacteria and fungi are important in the environment because they

recycle nutrients, making them available for other organisms

Sexually reproducing organisms pass on genetic information as a

sequence of the bases A, T, C, and G

Two kittens in a litter are genetically different from each other and from their parents. These genetic differences are most directly due to

sexual reproduction

Which list contains only abiotic conditions that might be found in a pond ecosystem?

temperature of the water, dissolved oxygen in the water, dissolved minerals in the water

Doctors often use certain medications to treat infections. A few people have a reaction to some of these medications, such as itching, swelling, or trouble breathing. This is an example of

the body's immune system overreacting to a usually harmless substance

Scientists who have examined the fossil record have noted that some species have changed very little over long periods of geologic time. The lack of change in such organisms is most likely because

the environment that they lived in remained the same, and they were well-adapted to it

A genetic change that occurs in a body cell of a mouse will not contribute to the evolution of the species because

the evolution of a species can result from changes in reproductive cells, not body cells

The diagram below represents various factors in an area.

the flow of materials in a forest community

One explanation for the timing and length of the leopard frog breeding season is that it occurs

when environmental conditions are most favorable