Questions 1-6 refer to the following study:
Heart Disease Study
In 1949, a study of heart disease included 5,137 adults: 2,292 men and 2,845 women. All the individuals were 49 to 70 years of age, and none showed any signs of coronary artery disease.
After 14-16 years of careful follow-up, it was found that:
- 151 men and 37 women showed evidence of coronary artery disease that would account for a heart attack.
- 102 men and 18 women died of coronary artery disease before they reached the age of 65.
- 58 percent of the men and 39 percent of the women died within one hour of having a heart attack.
- For both men and women, sudden death was more likely if they were under age 55 at the time of the attack.
- Not all heart attacks produce symptoms. A considerable number of men and women had a myocardial infarction (heart muscle damage) without knowing it. Of those who suffered such “silent coronaries,” 22% of the men and 35% of the women did not know muscle damage had occurred.
- In the design of this study, which of the following did the researchers ensure?
- Some individuals had coronary artery disease.
- Some individuals were in their thirties.
- The number of men and women was equal.
- All participants were adults.
All participants were adults (ages 49–70), and none had coronary artery disease at the start. The study did not ensure equal numbers of men/women or include people in their thirties.
- According to the study, which of the following is true about a person who has a silent coronary?
- They are unaware of any heart attack symptoms.
- They do not scream in pain while having a heart attack.
- They show no evidence of heart muscle damage.
- They always die of a myocardial infarction.
A silent coronary is a myocardial infarction that occurs without the person realizing it (no recognized symptoms), yet it still involves heart muscle damage.
- A woman who is 53 years old has a heart attack. Compared with a man, what is she more likely to do?
- Die of coronary artery disease before age 65
- Have a silent coronary
- Die within an hour of the attack
- Die as the result of a heart attack after age 65
Women were more likely than men to have silent heart attacks (22% of men vs 35% of women among those with silent coronaries). Men had higher one-hour fatality rates and more pre-65 CAD deaths.
- Which conclusion is consistent with the results of the study?
- Chances of death within one hour of a heart attack are greater for women than men.
- Chances of death from coronary artery disease are less for men than women.
- Evidence of coronary artery disease is equal among men and women.
- Sudden death is more likely for both men and women if they are under age 55 at the time of the attack.
The passage states outright that for both sexes, sudden death was more likely under age 55 at the time of the attack.
- Based on the results of this experiment, which of the following is true of the people who died of coronary artery disease before age 65?
- 18% were women.
- 20% were women.
- 85% were men.
- 102% were men.
Before age 65, 102 men and 18 women died of CAD.
\(\dfrac{102}{120} = 85% \text{ men}\)
- A group of 1,000 men and 1,200 women between the ages of 50 and 65 are to be studied for coronary artery disease. Based on the original study, which of the following results could be predicted most reliably?
- Eight women will die of coronary heart disease after they reach age 65.
- Sixteen women will show significant evidence of coronary artery disease.
- Forty-four men will die of coronary artery disease after they reach age 65.
- Sixty-five men will show no significant evidence of coronary artery disease.
From the original study, \(\frac{37}{2,845}\) women gives us about 1.30% that had CAD evidence.
Applied to 1,200 women, \(1,200 \times 0.013 \approx 15.6 \approx 16\).
Questions 7-12 refer to the following passage:
Litmus Paper Experiment
A chemistry student placed a strip of blue litmus paper and a strip of pink litmus paper in a glass dish. Then she added a drop of dilute sulfuric acid to each strip of litmus paper. She observed that the blue litmus paper turned pink, but the pink litmus paper did not change color. Next she placed a drop of sodium hydroxide (NaOH) on other strips of blue and pink litmus paper. This time, the pink litmus paper turned blue, but the blue litmus paper did not change. Finally, she put a drop of distilled water on strips of blue and pink litmus paper. Neither strip changed color. She repeated the tests several times with the same results. The student concluded that acids turn blue litmus paper pink; bases, such as sodium hydroxide, turn pink litmus paper blue. As water did not affect either pink or blue litmus paper, she reasoned that water was not an acid or a base, but a neutral substance.
Keeping these results in mind, the student poured a little sodium hydroxide into a beaker containing pink and blue litmus paper. Then she added hydrochloric acid (HCl) drop by drop until the solution became neutral. She determined that a new, neutral substance had formed in the beaker. The substance was table salt, or sodium chloride (NaCl), which is one of many salts formed from an acid and a base.
- If a drop of an unknown substance turns blue litmus paper pink but does not change pink litmus paper, what is the substance?
- Acid
- Base
- Water
- Salt
Acids turn blue litmus pink and leave pink litmus unchanged (it’s already the acid color).
- Which of the following occurs in the presence of potassium hydroxide?
- Blue litmus paper turns pink.
- Pink litmus paper turns blue.
- Blue litmus paper becomes darker.
- Pink litmus paper does not change.
Potassium hydroxide (KOH) is a base, and bases turn pink litmus blue (blue litmus stays blue).
- When strips of blue and pink litmus paper are put in a beaker filled with a clear solution, neither litmus paper changes color. The solution must be which of the following?
- Water
- Neutral
- An acid
- A base
If neither blue nor pink litmus changes, the solution is neutral.
- In another experiment, the student added hydrochloric acid drop by drop to a solution of sodium hydroxide containing strips of originally blue and originally pink litmus paper. As she continued adding acid, which of the following occurred?
- The pink litmus paper remained pink.
- The blue litmus paper remained blue.
- The blue litmus paper turned from pink back to blue.
- The pink litmus paper turned from blue back to pink.
Starting in NaOH (base), pink litmus has turned blue. As HCl is added and the solution moves toward neutral, that strip reverts to pink.
- Based on the results of the original experiment, when would a salt be formed?
- When NaCl is combined with NaOH
- When H2O is combined with HCl
- When KOH is combined with HCl
- When HCl is combined with H2OSO4
A salt forms from an acid-base reaction.
\(\text{KOH} + \text{HCl} \rightarrow \text{KCl} + \text{H}_2\text{O}\)
- In setting up an aquarium, several factors must be considered before introducing fish. Which of the following factors could be tested using litmus paper?
- Salinity
- Acidity
- Chlorination
- Temperature
Litmus paper detects acidity/alkalinity (pH), not salinity, chlorine level, or temperature.
Questions 13-18 refer to the following passage:
Stickleback Experiments
The complex behavior of the poor-sighted, three-spined male stickleback fish has been studied extensively as a model of species behavior in courtship and mating. After a male has migrated to a suitable spot, he builds a spawning nest of sand and sediment. In courting, he performs a special zigzag dance. The female then follows the male to the nest where she spawns and he fertilizes the spawned eggs. Also, male sticklebacks have been shown to exhibit territorial behaviors. A biologist performed three experiments to learn more about the behavior of the stickleback.
Experiment 1
Tank 1 and Tank 2 are set up with identical conditions and one male stickleback is placed in each tank. Both fish build nests in their respective tanks. The male from Tank 1 is removed from his tank and is replaced with an egg-laden female; the male from Tank 2 is removed from his tank and is introduced into Tank 1. In Tank 1, the male does not perform the zigzag dance and no spawning occurs. The male retreats to a corner of the tank.
Experiment 2
A male stickleback in an aquarium builds his nest. A fat, round male is introduced into the environment. The original male performs the zigzag dance and attempts to lead the round male to the nest. The round male refuses and begins to flap his fins and swim in circles. The first male then begins to flap his fins, circle his nest, and occasionally prod the other fish to a far corner of the tank.
Experiment 3
A small, flat-shaped female is introduced into a tank where a male has built a nest. The male circles the female a few times, and then retreats to a corner of the tank.
- The experimental data would support the hypothesis that which of the following is the purpose of the male stickleback’s mating dance?
- To keep away other male sticklebacks
- To fertilize the eggs
- To lure and entice the female to the nest
- To establish territorial rights
The male’s zigzag dance functions to lead a mate to the nest. In Experiment 2, he even tries to lead a round male (mistaken for a gravid female) to the nest.
- Based on observations from the experiments, which factor initially stimulates the male to do the zigzag dance?
- The physical environment
- The shape of the fish
- The number of fish in the tank
- The sex of the fish
The initial trigger is the shape resembling an egg-laden female.
The male danced for a fat, round male (Experiment 2), so sex alone can’t be the trigger, and “environment” didn’t elicit dancing in Experiment 1 after the swap.
- Which experiment supports the hypothesis that the male exhibits territorial behavior?
- Experiment 1
- Experiment 2
- Experiments 1 and 2
- Experiments 1, 2, and 3
Territorial behavior appears in Experiment 2. Experiments 1 and 3 describe retreating, not defense.
- To further investigate the territorial behavior of the stickleback, the biologist should vary which of the following factors in Experiment 2?
- The temperature of the water
- The fatness of the male fish
- The sediment and sand in the tank
- The size of the tank
To probe territoriality, vary space to see how territory establishment/defense changes.
- To clarify the results of Experiment 1, the biologist should set up which of the following test situations?
- Maintain the positions of the male sticklebacks and add another egg-laden female to Tank 1.
- Place both male sticklebacks in Tank 2.
- Return the original male stickleback to Tank 1 and observe its behavior with the female fish.
- Repeat the experiment using a different species of fish.
Returning the original male to Tank 1 with the egg-laden female tests whether his lack of dancing was due to loss of territory/nest cues rather than the female herself.
- A male stickleback has been established in an aquarium and has built a nest. If one egg-laden female and several flat-shaped male sticklebacks are placed in the tank, what would most likely occur?
- All the males would perform the zigzag dance.
- All the males would circle the female.
- Only the male that was originally in the tank would perform the zigzag dance.
- The female would retreat to a corner.
The resident male with the established nest is most likely to perform the mating dance for the egg-laden female; the flat-shaped males wouldn’t trigger his courtship and are more likely to be repelled.