Which of the following is the most appropriate first step for each student to undertake?

• Test a variable

• Write a theory

• Decide on a hypothesis to test

• Gather and set up materials

Answer explanation

A hypothesis a guess that you can test. Once observations are made, the experimenter must decide what to test before gathering material and exeperimenting.

Tags

NGSS.MS-LS1-1

NGSS.MS-PS2-2

What is the independent variable?

• Seed Germination

• Conditions

• Amount of Water

• Cannot be determined

Answer explanation

The independent variable is changed or altered on purpose (I change it). Conditions such as temperature or light can be chanced on purpose by the experimenter.

Tags

NGSS.MS-LS1-5

This experiment was most likely designed to determine which of the following?

• The most effective enzyme concentration for enzyme activity

• The most effective pH for enzyme activity

• Whether the enzyme adversely affects bacterial cells

• Whether pH changes stimulate bacterial cell division

Answer explanation

The pH of the enzyme was adjusted and the activity (light transmission was measure). Low and high enzyme pH resulted in less activity or light transmission.

Which of the following is the dependent variable in the experiment described?

• The catalytic activity of the enzyme

• The temperature at which the experiment was conducted

• The concentration of enzyme used

• The concentration of the stock bacterial solution

Answer explanation

The dependent variable is the data or results. The enzyme's activity (light transmission) is the experimental data.

Tags

NGSS.HS-PS1-5

Based on the data in the table, which pH results in the greatest disruption of bacterial cell structure?

• 3

• 5

• 7

• 11

Answer explanation

At pH 7, the enzyme had the best activity (68% light transmission).

One of the students decided to test the following hypothesis: Seeds need light to germinate. Which of the following experimental designs would be the most appropriate to test this hypothesis?

• A. Plant ten seeds in soil and place them in a dark cabinet.

• B. Place ten seeds on moist filter paper and place them on the windowsill. Place another ten seeds on moist filter paper and place them in a dark cabinet.

• C. Place one seed in a dish of water under a light. Place another seed of the same type in a dish of water in a dark cabinet.

• D. Put a full-grown geranium plant in the light and another full-grown plant of the same type in the dark.

Answer explanation

Choice B is the best design as it compares germination of seeds in light versus dark conditions, using equal numbers of seeds in both environments to test the hypothesis effectively.

Tags

NGSS.MS-LS1-5

NGSS.MS-LS2-1

Many protists are single-celled organisms, as are bacteria. However, protists and bacteria are in different biological kingdoms. Which 2 comparisons of protists and bacteria is NOT true?

• Both protists and bacteria can be motile. 

• Both protists and bacteria are prokaryotes.

• Protists are eukaryotes, while bacteria are prokaryotes. 

• Protists may be photosynthetic, and bacteria can only be autotrophs.

Answer explanation

The statement 'Both protists and bacteria are prokaryotes' is false because protists are eukaryotes. Additionally, the claim that 'bacteria can only be autotrophs' is incorrect; bacteria can also be heterotrophic.

Tags

NGSS.MS-LS4-2

The correct order of the biological hierarchy from largest to smallest is:

• Domain, kingdom, class, family, order, phylum, genus, species. 

• Kingdom, phylum, order, family, class, genus, species, domain. 

• Domain, kingdom, phylum, class, order, family, genus, species.

• Kingdom, class, order, phylum, family, genus, species, domain.

Answer explanation

Proper order of Biological hierarchy from largest to smallest: Domain, kingdom, phylum, class, order, family, genus, species.

Refer to the cladogram and the animal pictures.

Which organism has amniotic eggs?

• 
• 
• 
• 

Answer explanation

In the diagram, Prosimians would be placed to the RIGHT of vertebrates, four legs, amniotic eggs and hair. Frogs have 4 legs but lack amniotic fluid. Therefore, prosimian is the correct answer.

Tags

NGSS.MS-LS4-1

Which organism has a backbone but LACKS 4 legs?

• A. Prosimians

• B. Amphibians

• C. Insects

• Fish

Answer explanation

Insects have NO backbone and are invertebrates. Fish have a backbone, but do not have 4 limbs. So fish is the correct answer.

Tags

NGSS.MS-LS4-2