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?

   • A new enzyme that the seed made on purpose
   • The same enzyme, made in a larger amount
   • No starch-building enzyme is made
   • Wrinkled seeds, the trait itself
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 extra sugar fills the seed
   • Wrinkled seeds, since the seeds chose the shape
   • Round seeds, since the gene is still in the cell
   • Wrinkled seeds, since they shrink as they dry
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
   • A whole chromosome, since a gene is bigger
   • The whole nucleus, since DNA is bigger
   • One gene, a short section of DNA
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?

   • No effect, since the bacteria look the same
   • Harmful, since a DNA change breaks the cell
   • Helpful, since the bacteria can use a food
   • Helpful, since the bacteria planned the change
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
   • Harmful, since a mutation is a harmful change
   • No effect, since a DNA change is tiny
   • Harmful, since the leaves cannot make food
6. 6.

   Luz reads that one DNA letter in a bean plant's gene changed, but the protein it makes is the same. The plant looks the same. How is the change best described?

   • Harmful, since the DNA letter changed
   • Helpful, since a new letter gives a new trait
   • Helpful, since the plant needed the new letter
   • No effect, since the protein stays the same
7. 7.

   46 chromosomes, in pairs. Milo reads that a human cell has 46 chromosomes in pairs, one of each pair from each parent. How many pairs are there?

   • 23 pairs, since each pair has two chromosomes
   • 2 pairs, since there are two parents
   • 92 pairs, since each parent gives 46 pairs
   • 46 pairs, since each chromosome is its own pair
8. 8.

   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 12 chromosomes, and each holds many genes
   • It has 24 genes, and each holds many chromosomes
   • It has 24 chromosomes, each holding many genes
   • It has 12 chromosomes, and each gene holds many
9. 9.

   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?

   • Yes, a plant changes its DNA when it needs to
   • No, DNA stays the same for the plant's whole life
   • Yes, dim light tells the DNA how to change
   • No, DNA changes happen by chance, not by need
10. 10.

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

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