4/17/23 Warm up

Scientific claims should be questioned if

• peer review was used to examine the claims made by scientists

• the experimental results cannot be repeated by other scientists

• conclusions follow logically from the evidence

• the data are based on samples that are very large

The graph pictured represents the rate of a chemical reaction involving a particular human enzyme that breaks down starch. The most likely reason the action of the enzyme decreases after 40°C is that

• the DNA in the enzyme mutates and can no longer break down the starch

• enzymes die after working for a long period of constant activity in the body

• the shape of the enzyme changes due to environmental conditions

• as the temperature of the enzyme rises, the pH of the environment changes, deactivating the enzyme

The diagram pictured represents one of a number of different types of mutations that can occur in DNA. This mutation can best be described as the

• pairing of an adenine (A) base with thymine (T)

• the insertion of an adenine (A) base into both strands of the DNA molecule

• the substitution of an adenine (A) base for guanine (G)

• deletion of an adenine (A) base from the DNA molecule

Some salmon have been genetically modifi ed to grow bigger at a faster rate than wild salmon. They are kept in fish-farming facilities and are not released into the wild. Which statement regarding genetically modified salmon is most likely true?

• Wild salmon reproduce sexually, while genetically modified salmon reproduce asexually

• Wild salmon have an altered protein sequence, but genetically modified salmon do not.

• Genetically modified salmon and wild salmon would have different DNA sequences.

• Genetically modified salmon and wild salmon would have identical DNA sequences.

Which statement is the most likely explanation for the color differences in the fur of the fox at different times of the year?

• Mutations can be caused by changes in the number of biotic factors in the environment.

• The expression of genes can be modified by the external environment.

• Hereditary information is contained in genes located in the chromosomes of each cell.

• Random changes in DNA can occur to change the expression of a gene.

Which graph below best represents the relationship between the relative number of nuclei, genes, and chromosomes in a typical human cell?

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Sexually reproduced offspring have traits similar to their parents because they receive

• all of the proteins from each parent

• some of the proteins from both parents

• all of the genes present in both parents

• some of the genes present in each parent

The diagram pictured represents part of a biological process that begins with a chromosome containing a specific human gene being removed from a human cell. The overall process is important because it

• may be used to make human DNA identical to that of other organisms

• helps scientists understand how amino acids are grouped together to form a genetic code

• results in the production of carbohydrates that cannot mutate and cause disease

• may be used to produce chemicals that can be used to treat certain human disorders

Each of the cells present in a woman contains a complete set of chromosomes. The only exceptions are her

• skin cells

• egg cells

• nerve cells

• lung cells

A student read that liquid extracted from an Aloe vera plant promotes the healing of burned tissue. She decided to investigate the effect of different concentrations of Aloe vera extract on the regeneration (regrowth of lost or damaged tissue) rate in planaria. Planaria are small flatworms known for their ability to regenerate.

The student used a sterile scalpel to cut each of 30 planaria in half. This gave her 10 heads and 10 tails for each of three experimental groups. The planaria were kept in separate Petri dishes in the same amount of water and at the same temperature. Group 1 received 0% Aloe vera extract, Group 2 received a 20% concentration of the extract, and Group 3 received a 40% concentration. On days 7, 10, and 14, she recorded the amount of tissue regeneration in all three groups. She observed that the group with 20% Aloe vera added regenerated more slowly than the group with 40% added.

A reasonable inference based on these results would be that

• Aloe vera affected the rate of cell division, resulting in an increased rate of regeneration

• the control group, which received no Aloe vera, did not regenerate

• if she applied 30% Aloe vera to a group, it would regenerate tissue more rapidly than the 40% group

• the application of Aloe vera to earthworms would have no effect on tissue regeneration