Scientific Practice

When was the average snowfall for Chicago higher than the average snowfall for New York?

• January & Febuary
• February & March 
• June & July
• November & December

Testosterone oxido-reductase is a liver enzyme that regulates testosterone levels in alligators. One study compared testosterone oxido-reductase activity between male and female alligators from Lake Woodruff, a relatively pristine environment, and from Lake Apopka, an area that has suffered severe contamination. The graph above depicts the findings of that study.

The data in the graph best support which of the following claims?

• Environmental contamination elevates total testosterone oxido-reductase activity in females.

• Environmental contamination reduces total testosterone oxido-reductase activity in females.

• Environmental contamination elevates total testosterone oxido-reductase activity in males.

• Environmental contamination reduces total testosterone oxido-reductase activity in males. 

Tags

NGSS.MS-LS1-5

NGSS.MS-LS2-4

A group of students designed an experiment to determine the effect of compost on the germination and growth of plants. The students set up experimental plots by mixing different ratios of soil and compost. They planted 20 pea and 20 melon seeds in each plot and watered each plot regularly. The students recorded the number of seeds that germinated, and as the plants grew, they recorded plant length, number and size of leaves, and general health observations.

The following observations were recorded.

-In all treatments, more pea seeds germinated than melon seeds.

-There was a week of rainy weather at three weeks.

-Melon plants developed a fungal growth at four weeks.

-Melon plants grew longer than pea plants, but many melon leaves showed signs of yellowing as the weeks passed.

The students concluded that pea plants grew better in compost than did melon plants.

Which of the following best addresses the validity of the conclusion made by the students?

• The conclusion is valid because the independent and dependent variables in the experiment were controlled.

• The conclusion is valid because the experimental design included a large sample size.

• The conclusion is invalid because other variables in the experiment (both biotic and abiotic) affected the results.

• he conclusion is invalid because the units of measurement were not given in the experimental design.

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-4

Dory set up an experiment to see how the mass of a ball affects the distance it rolls off a ramp. What is the dependent variable?

• distance traveled by the ball
• height of the ramp
• mass of the ball
• ball type

Tags

NGSS.MS-PS2-2

A researcher designs an experiment to investigate the effect of environmental temperature on the function of an enzyme. For each trial included in the experiment, the researcher will add the enzyme and its substrate to an aqueous buffer solution and then measure the amount of product formed over 20 minutes.

Which of the following must remain the same for all trials of this experiment?

• The initial concentration of the substrate

• The final concentration of the product

• The three-dimensional structure of the enzyme

• The temperature of the aqueous buffer solution

Tags

NGSS.MS-ETS1-1

Which significance level  
(column) do you look at when finding the critical value?

• .50
• .10
• .05
• .01

A scientist is evaluating a proposal for raising large numbers of fish in ocean pens for human consumption. As part of the evaluation, the scientist is designing a plan for investigating how the fish in the ocean pens might affect nearby ecosystems.

Which of the following is the most appropriate factor to use as the dependent variable in the experimental investigation?

• The amount of metabolic wastes in the water where the fish are being raised

• The water temperature in the natural habitat of the fish being studied

• The types of fish that are preferentially consumed by humans

• The amount of time it takes for fish to digest a meal

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-3

NGSS.MS-LS2-4

A researcher observes that when two heterozygous plants with red flowers are crossed, the resulting offspring include plants with red, white, or pink flowers. The researcher proposes the null hypothesis that flower color is the result of independent assortment and incomplete dominance.

The researcher calculates a chi-square value of 7.3. Assuming two degrees of freedom, which of the following is the correct interpretation of the chi-square analysis, using a p-value of 0.05?

• The null hypothesis should be rejected because the critical value is less than the calculated value.

• The null hypothesis should not be rejected because the critical value is less than the calculated value.

• The null hypothesis should not be rejected because the critical value is greater than the calculated value.

• The null hypothesis should be rejected because the critical value is greater than the calculated value.

Tags

NGSS.MS-LS3-2

NGSS.MS-LS4-4

A spherical bacterial cell has a radius of 3μm. The human egg cell has a radius of 100μm.

Which statement correctly indicates the cell that is able to more efficiently exchange materials with the external environment and provides a correct explanation?

• The egg cell, because it has the smallest surface-to-volume ratio.

• The egg cell, because it has the largest surface-to-volume ratio.

• The bacterial cell, because it has the smallest surface-to-volume ratio.

• The bacterial cell, because it has the largest surface-to-volume ratio.

An experiment is performed on plants to see how different liquids affect plant growth. Each plant in the experiment is given a different liquid: water, apple juice, or milk. What variables should be kept constant/controlled? 

• type of plant, flower pot,  soil, and amount of sunlight
• water, apple juice, milk
• only the amount of sunlight
• type of plant only