biology pltl 2/2

How does a scientific theory differ from a scientific hypothesis?

• A theory is an explanation for a very general phenomenon or observation; hypotheses treat more specific observations

• Theories define scientific laws; hypotheses are used to set up experiments

• A hypothesis is an explanation for a very general phenomenon; theories treat more specific issues

• Theories are proposed to test scientific hypotheses

Your microwave will not turn on, and you speculate that a circuit breaker in the house has been tripped. In scientific terminology, the steps would be described as:

• Developing a hypothesis based on observation

• Testing a prediction generated from a hypothesis

• Forming conclusions from the results of experiments

• Developing an observation based on a hypothesis

A student poses the question: How does the presence of dissolved salt affect the freezing point of water? To answer this question, the student set up two conditions. In the first condition, the student added salt to water in a container and referred to this condition as the variable. In the second condition, the student did not add any salt to water in a second container and referred to this condition as the control. The student took both containers and attempted to freeze the water at various temperatures to assess the freezing point. Would this be a valid experiment?

• No, because there is not more than one variable

• No, because there is only one variable

• Yes, because there is more than one variable

• Yes, because there is one variable and a control

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

NGSS.MS-PS3-5

A student set up an experiment to test if plants give off water vapor. Fifty pea plants, growing in pots, were covered with individual glass containers and left overnight. The next morning, the inside of each lid was covered in droplets of water. The lab student concluded that plants generally give off water vapor. What critique would you make of the experimental design?

• The student did not have a clearly stated hypothesis before beginning the experiment.

• There was no control so the water could have come from other sources such as ai in the jar or the soil.

• The experiment was not precise meaning it was not reproducible

• There was not a large enough sample of pea plants used to get adequate data.

Tags

NGSS.HS-ETS1-3

It is known that many trees lose their leaves in response to decreasing day length. As a result, you think that Ginkgo trees may also lose their leaves in response to decreasing day length. This statement is an example of:

• Deductive reasoning

• A theory

• An experiment

• Hypothesis

Phil is conducting a seed germination experiment. He places 3 groups of lettuce seeds in a 34 degree Celsius incubator with adequate moisture. One set of seeds is placed in a dark area with no light source. A second set is placed under artificial light and third set of seeds is placed in direct sunlight. This experiment is intended to test Phil's hypothesis that light is necessary for lettuce seed germination.

Based on the experimental design, which variable was the control?

• Seeds in the dark

• Germination rate

• Temperature

• Moisture

• Type of light

Based on the experimental design, which variable was the dependent variable?

• Germination rate

• Type of light

• moisture

• seeds in the dark

• temperature

• Molybdenum has an atomic number of 42. Several common isotopes exist, with mass numbers from 92-100. Therefore, which of the following can be true?

• Molybdenum atoms can have between 50 and 58 protons

• Isotopes of molybdenum have different numbers of elections

• Molybdenum atoms can have between 50 and 58 neutrons

• Molybdenum atoms can have between 50 and 58 electrons

Tags

NGSS.HS-PS1-8

• Carbon-12 is the most common isotope of carbon and has a mass number of 12. However, the average atomic mass of carbon found on a periodic table is slightly more than 12 Daltons. Why?

• Some carbon atoms in nature have an extra proton

• The atomic mass does not include the mass of electrons

• Some carbon atoms in nature have more neutrons

• Some carbon atoms in nature have a different valence electron distribution

Tags

NGSS.HS-PS1-8

• Fluorine has an atomic number of 9. Which of the following would you do to a neutral fluorine atom to complete its valence shell?

• Add 1 electron

• Remove 1 electron

• Add 2 electrons

• Nothing, if fluorine is neutral, it has a complete valance shell

Tags

NGSS.HS-PS1-1