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IB DP Biology- B3.2 Transport- IB Style Questions For HL Paper 1A -FA 2025

IBDP Biology HL Paper 1 -FA 2025- All Chapters

Question

The graph below shows how blood pressure varies during the cardiac cycle, recorded using a sphygmomanometer. A cuff is placed on the upper arm, inflated to temporarily block blood flow in the artery, and then gradually released.

From the graph, determine the approximate values of the diastolic and systolic pressures.

 Diastolic pressure / mmHgSystolic pressure / mmHg
A.12076
B.13066
C.76120
D.66130
▶️ Answer/Explanation
The systolic pressure is the highest pressure reached during ventricular contraction (the first pulse detected as the cuff deflates), while the diastolic pressure is the lowest pressure before the sound disappears.
From the graph, these correspond approximately to 120 mmHg and 76 mmHg respectively.
✅ Answer: (C) 76 mmHg diastolic and 120 mmHg systolic

Question

The micrograph shows the cross-section of the vascular tissue in a dicotyledonous root. Which letter identifies phloem sieve tubes?

▶️Answer/Explanation

Answer: C

Explanation:

Structure Identification:

A – Xylem

  • Large, thick-walled, centrally located
  • Main job = Transport of water & minerals from root to shoot

B – Phloem (Sieve Tubes)

  • Found between the arms of xylem
  • Main job = Transport of organic nutrients (like glucose/sucrose)

C – Phloem Companion Cells or associated phloem tissue

  • Supports sieve tube elements
  • Helps with loading and unloading sugars

D – Endodermis

  • Surrounds vascular bundle
  • Has Casparian strip that controls water & nutrient entry into xylem
  • Like the root’s bouncer.
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