7th Grade Semester 2 Review 2024

Samantha and Jason were researching and investigating for their upcoming science in February. They both decided to investigate bacterial growth from the school’s water fountains after learning about genetics and reproduction at McLane Middle School. Both grew the samples in petri dishes from the same source (their teacher) and counted the number of bacteria for their individual samples for the same period. Below is the number of cells that grew in 4 days .Based on the graph, what conclusion can be made about the two experiments?

• By providing more nutrients they can replicate the experiment and double growth.

• Another student repeats the experiment with bacteria from a different school.

• The measurements are not accurate because they do not repeat the experiment.

• Bacteria growth was greater for one student than the other therefore the results are not replicated.

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Biologists study living organisms. To learn more about humans, biologists often have mice in their labs. Why might a biologist use mice in their pursuit of scientific explanations of humans?

• Mice and humans look alike.

• Mice are smarter than humans.

• Mice and humans are genetically similar.

• Mice eat a lot and do not move very much.

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Building models can help scientists make discoveries about the natural world. For example, scientists used cardboard cutouts of the chemical substances that make up the molecule responsible for heredity. This molecule is known as DNA. The scientists put together the cardboard cutouts along with other materials to build their model. This model helped the scientists determine the structure of the DNA molecule. What type of model did scientists construct to help them determine the structure of the DNA molecule?

• a physical model

• a computer model

• a conceptual model

• a mathematical model

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NGSS.MS-LS3-1

Explain the relationship between DNA, chromosomes, genes, and the traits passed from parent to offspring.

• Chromosomes are comprised of segments of DNA called genes that control the traits that will be passed from parent to offspring.

• DNA comprises segments of chromosomes called genes that control the traits passed from parents to offspring.

• Genes are comprised of segments of chromosomes called DNA that control the traits that will be passed from parents to offspring.

• Chromosomes are comprised of segments of genes called DNA that control the traits that will be passed from parents to offspring.

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The expected number of chromosomes in human body cells is 46. Fruit flies have only 8 chromosomes, mulberry trees have 308, and protists can have thousands. Dogs are in the middle of the range, with 78 chromosomes. How many chromosomes are in the sex cells of each of these organisms?

• always 23

• always half as many as in the body cells

• always as many as in the body cells

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What is the relationship between genes and chromosomes?

• Genes are made up of thousands of chromosomes.

• Genes are segments of DNA on each cell's chromosomes.

• Genes correspond to the phenotype, while chromosomes correspond to the genotype.

• Chromosomes correspond to the phenotype, while genes correspond to the genotype.

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Which reason best explains why the ability to reproduce asexually is a desirable characteristic for a research organism?

• Researchers will not have to find mating pairs.

• All offspring of an individual will be genetically identical.

• There will be fewer generations than there would be with sexual reproduction.

• Organisms that reproduce asexually have less DNA than organisms that reproduce sexually.

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NGSS.MS-LS3-2

Which statement correctly describes the mechanisms of cell division?

• Mitosis produces sex cells; meiosis produces body cells.

• Meiosis produces genetically identical cells; mitosis does not.

• Meiosis is a form of asexual reproduction; mitosis is a form of sexual reproduction.

• Mitosis produces genetically identical cells; meiosis does not.

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The gene for a large-size fruits (L) in tomato plants is dominant over the gene for small-size fruits in tomato plants (l). If Marcus crosses a heterozygous parent plant with a homozygous recessive parent plant, what is the probability of the offspring having large-size fruits?

• 100%

• 50%

• 75%

• 25%

What is the definition of a DNA mutation?

• The original DNA strands.

• The strand with four pairs.

• Change in the DNA strand.

• The strand in a double helix.

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