Genes, chromosomes and mutations

Grade 7 Science Worksheet

Circle the best answer.

1. 1.

   Ari traces a change in pea seeds. A piece of DNA is inserted in the SBE1 gene. What goes in the Protein box?

   • The same enzyme, made in a larger amount
   • Wrinkled seeds, the trait itself
   • A new enzyme that the seed made on purpose
   • No starch-building enzyme is made
2. 2.

   Bo reads that seeds without the enzyme hold less starch and more sugar, then take in water and dry. What goes in the Trait box?

   • Round seeds, since the gene is still in the cell
   • Wrinkled seeds, since they shrink as they dry
   • Round seeds, since extra sugar fills the seed
   • Wrinkled seeds, since the seeds chose the shape
3. 3.

   Esme asks what part of the pea cell the inserted piece changed. Which description fits the Gene box?

   • The seed shape, since a gene is a trait
   • The whole nucleus, since DNA is bigger
   • One gene, a short section of DNA
   • A whole chromosome, since a gene is bigger
4. 4.

   Jun reads about E. coli bacteria in a lab flask with citrate and little other food. A DNA change lets some bacteria use citrate. How is the change best described?

   • Helpful, since the bacteria planned the change
   • Harmful, since a DNA change breaks the cell
   • No effect, since the bacteria look the same
   • Helpful, since the bacteria can use a food
5. 5.

   Kira reads that a cucumber seedling has a DNA change. Its leaves have no chlorophyll and look pale. Chlorophyll absorbs light for making food. How is the change best described?

   • Helpful, since pale leaves stay cooler
   • No effect, since a DNA change is tiny
   • Harmful, since a mutation is a harmful change
   • Harmful, since the leaves cannot make food
6. 6.

   Noah reads that a fruit fly cell has 4 pairs of chromosomes. How many chromosomes is that in total?

   • 2 chromosomes, since a fly has two parents
   • 4 chromosomes, since a pair counts as one
   • 8 chromosomes, since each pair has two
   • 16 chromosomes, since each pair has four
7. 7.

   Pia reads that a rice plant cell has 12 pairs of chromosomes. Each chromosome is made of DNA and holds many genes. Which statement is correct?

   • It has 24 chromosomes, each holding many genes
   • It has 12 chromosomes, and each gene holds many
   • It has 24 genes, and each holds many chromosomes
   • It has 12 chromosomes, and each holds many genes
8. 8.

   A basil plant sits in a dim room. Ren wonders if the plant changes its DNA on purpose to use the dim light. Which answer is best?

   • No, DNA changes happen by chance, not by need
   • Yes, dim light tells the DNA how to change
   • No, DNA stays the same for the plant's whole life
   • Yes, a plant changes its DNA when it needs to
9. 9.

   A pea bed is dry. Tala asks if the dry soil makes the helpful DNA changes. Which answer is best?

   • Yes, plants make the changes they need
   • No, a change comes by chance, helpful or not
   • Yes, dry soil makes changes that help
   • No, dry soil cannot affect anything in a plant
10. 10.

    A new DNA change helps one pea plant in a dry bed. Zee asks why that plant has it. Which explanation fits?

    • A DNA change gives a plant a helpful new trait
    • A chance change; dry soil showed it helps
    • The dry soil put the change into the seed
    • The plant made the change because the bed was dry