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TEAS 7 Science: Biology practice questions

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These are original practice items written to the TEAS 7 blueprint (4 options, no penalty for wrong answers), not actual exam questions. Try each one before you open the answer.

What this topic covers

Science: Biology sits inside the Science section of the TEAS 7. Our bank holds 76 verified items tagged to it, and the 4 below are a fixed sample so the page stays the same every time you open it. Each one shows the reasoning, not just the letter.

The topic tag comes from our own items rather than from a published syllabus, so treat it as a map of what we cover. For the official section breakdown see the TEAS 7 page.

Science: Biology sample questions

Question 1

During DNA replication, which enzyme is responsible for unwinding the double helix ahead of the replication fork?

  1. A Ligase
  2. B DNA polymerase
  3. C Helicase
  4. D Primase
Show the answer and explanation

Correct answer: C

Helicase breaks the hydrogen bonds between complementary base pairs, unwinding the DNA double helix to create two single strands that serve as templates. DNA polymerase synthesizes new strands. Ligase joins Okazaki fragments on the lagging strand. Primase synthesizes RNA primers.

Why the other options are wrong:
A: Ligase seals nicks in the sugar-phosphate backbone, it does not unwind DNA.
B: DNA polymerase adds nucleotides to the growing strand but does not unwind the helix.
D: Primase synthesizes short RNA primers needed for DNA polymerase to start, but does not unwind the helix.

Question 2

A student examines a cell undergoing division. She observes that homologous chromosomes are paired up and crossing over is occurring. This cell is most likely in which phase of meiosis?

  1. A Prophase II
  2. B Metaphase I
  3. C Anaphase II
  4. D Prophase I
Show the answer and explanation

Correct answer: D

Crossing over of homologous chromosomes occurs only during prophase I of meiosis. In metaphase I, homologous pairs align but crossing over has already finished. Prophase II and anaphase II involve sister chromatids, not homologous pairs.

Why the other options are wrong:
A: Prophase II occurs after meiosis I; cells are haploid and no homologous pairs exist.
B: In metaphase I, homologous pairs are aligned but crossing over has already ended.
C: Anaphase II involves separation of sister chromatids, not homologous pairing.

Question 3

During cellular respiration, the majority of ATP is produced in which process?

  1. A Glycolysis
  2. B Electron transport chain
  3. C Fermentation
  4. D Krebs cycle
Show the answer and explanation

Correct answer: B

The electron transport chain (ETC) produces about 34 molecules of ATP per glucose molecule, far more than glycolysis (net 2 ATP) or the Krebs cycle (2 ATP). Fermentation yields only 2 ATP per glucose.

Why the other options are wrong:
A: Glycolysis yields a net gain of only 2 ATP per glucose.
C: Fermentation is an anaerobic process that yields only 2 ATP per glucose.
D: The Krebs cycle produces only 2 ATP per glucose.

Question 4

Which of the following correctly describes a key feature of DNA replication?

  1. A It occurs in the cytoplasm of eukaryotic cells.
  2. B It is semiconservative, meaning each new DNA molecule contains one old strand and one new strand.
  3. C It begins at the telomeres located at the ends of chromosomes.
  4. D It is a conservative process that preserves the original DNA molecule intact.
Show the answer and explanation

Correct answer: B

DNA replication in cells is semiconservative: each original strand serves as a template for a new complementary strand, so each daughter molecule has one parent strand and one newly synthesized strand. In eukaryotes, replication occurs in the nucleus, not the cytoplasm, and begins at multiple origins, not at telomeres.

Why the other options are wrong:
A: In eukaryotes, DNA replication occurs in the nucleus, not the cytoplasm.
C: Replication begins at specific origins of replication along the chromosome, not at the telomeres.
D: DNA replication is not conservative; the original strands separate and both serve as templates.

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