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Pre AP Biology -GEN 4.3 Chromosomal Disorders- FRQ Exam Style Questions -New Syllabus

Pre AP Biology -GEN 4.3 Chromosomal Disorders- FRQ Exam Style Questions – New Syllabus 2025-2026

Pre AP Biology -GEN 4.3 Chromosomal Disorders- FRQ Exam Style Questions – Pre AP Biology – per latest Pre AP Biology Syllabus.

Pre AP Biology – FRQ Exam Style Questions- All Topics

Question

Vitamin B3 deficiency has been linked to a higher incidence of miscarriage and foetal abnormalities.
A study was conducted to test the effect of vitamin B3 during pregnancy on the fetus.
  • (500) pregnant women were randomly allocated into two groups.
  • One group of (250) women were given Vitamin B3 tablets throughout the pregnancy (intervention group) and the control group were given a placebo (sugar tablets) during their pregnancy.
  • During the study, (10) women had miscarriages from the intervention group and (9) women had miscarriages from the control group.
  • After birth, the infants were assessed for any abnormalities. Among the mothers that took the Vitamin B3, (4) infants were born with abnormalities. Among the control group, (15) infants were born with abnormalities.
(a) Evaluate the method used in the epidemiological study in determining a link between Vitamin B3 deficiency and miscarriage and foetal abnormalities.
(b) Justify conclusions that could be drawn from the results of the study.

Most-appropriate topic codes (Pre-AP Biology):

• TOPIC: ECO 2.2 — Population Growth: Use data to explain patterns and the relationship between resource availability and growth/survival — parts (a), (b)
• TOPIC: GEN 4.3 — Chromosomal Disorders: Predict how altered development and conditions affect organisms — context and part (b)
• Science Area of Focus — Strategic Use of Mathematics: Analyze and interpret data collected while investigating the natural world to reveal patterns — parts (a), (b)
• Science Area of Focus — Emphasis on Analytical Reading and Writing: Extract and synthesize complex information from texts and representations to develop scientific arguments — parts (a), (b)
▶️ Answer/Explanation
Detailed solution

(a) Evaluation of the Method:
The study utilizes a randomized controlled trial design, which is a highly valid method for determining cause-and-effect relationships in epidemiology.

  • Randomization: Randomly allocating the (500) women minimizes selection bias, ensuring that both groups (intervention and control) are likely to have a similar distribution of extraneous variables (e.g., age, diet, socioeconomic status) at the start of the study.
  • Placebo Control: Using a placebo (sugar tablet) for the control group allows for a valid comparison by isolating the specific physiological effect of Vitamin B3. It helps negate the “placebo effect” where participants might feel better simply because they are being treated.
  • Sample Size: A sample size of (500) ((250) per group) is reasonably large, which increases the statistical reliability of the results and reduces the impact of outliers.
  • Intervention Duration: Administering the tablets “throughout the pregnancy” ensures the variable is tested during all critical stages of fetal development.

(b) Justification of Conclusions:
Based on the numerical data provided, two distinct conclusions can be drawn:

  1. Vitamin B3 has no significant effect on the risk of miscarriage.
    Justification: The incidence of miscarriage was almost identical between the two groups, with (10) miscarriages in the intervention group compared to (9) in the control group. This negligible difference suggests the supplement did not influence miscarriage rates.
  2. Vitamin B3 supplementation significantly reduces the risk of fetal abnormalities.
    Justification: There is a substantial difference in the results regarding abnormalities. The control group had nearly four times as many cases of abnormalities ((15) infants) compared to the intervention group ((4) infants). This data strongly supports the conclusion that taking Vitamin B3 lowers the incidence of fetal abnormalities.
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