DNA, Genes & Chromosomes — Practice · Grade 7 Science

Chapter: Genes, Cell Division & Heredity

What this practice covers

By the end of DNA, Genes & Chromosomes you should be able to:

8 questions, written answer and multiple choice, each with a worked explanation.

Vocabulary used: DNA, gene, allele, chromosome, phenotype.

Problem 1

Is a gene normally a whole chromosome?
Answer and explanation

No. A gene is a region of genetic material; a chromosome contains many regions and other DNA.

Problem 2

Why is “DNA letters directly become an eye color” incomplete?
Answer and explanation

Genetic information affects cellular products and processes; traits emerge through those processes and often involve several influences.

Problem 3

Can a capital letter alone prove dominance in a real organism?
Answer and explanation

No. Dominance describes an observed relationship between allele effects in a specified model, not a property of typography.

Problem 4

Why are complex traits poorly represented by one letter pair?
Answer and explanation

Several genetic and environmental contributions can interact; the one-pair model omits them.

Problem 5

Illustrative draft places a chromosome inside one gene and says every body cell with the same DNA performs the same task. Repair the nested relationship and explain cell specialization without inventing separate inherited genomes for every cell type.
Answer and explanation

Gene regions are parts of chromosome DNA, not containers for whole chromosomes. Cells with broadly similar genetic information can use different portions and develop different structures and roles. The model does not show every gene, product, or interaction, so a shared genome does not imply identical activity in all cells.

Place gene regions along chromosome DNA.

Connect information use with functional products.

Distinguish shared information from identical activity.

Response criteria

  • Explain the relevant biological process accurately.
  • Use the supplied evidence and show calculation steps with units where needed.
  • Connect a labeled model or mechanism with the claim.
  • State an assumption, evidence limitation, or useful next observation.

Problem 6

A fictional trait has alleles labeled P and p, but no relationship is supplied. Can its appearance be inferred from Pp alone?
Answer and explanation

No. The genotype letters identify versions under the model, but the genotype-phenotype relationship must be specified or supported by evidence.

Response criteria

  • Explain the relevant biological process accurately.
  • Use the supplied evidence and show calculation steps with units where needed.
  • Connect a labeled model or mechanism with the claim.
  • State an assumption, evidence limitation, or useful next observation.

Problem 7

Which relationship is correct?
  1. A gene contains every chromosome
  2. A chromosome contains DNA with many gene regions
  3. DNA is an organ
  4. Alleles are whole species
Answer and explanation

A chromosome contains DNA with many gene regions

Gene regions occur within genetic material organized into chromosomes.

Problem 8

How can two cells with similar DNA have different functions?
Answer and explanation

They can use different parts of the information and develop different structures and cellular activities.

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