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Science Biology — LET Practice Questions

This Science Biology section of the LET General Education exam covers 8 expert-reviewed practice questions. Each question has a plain-English explanation and notes on why the wrong answers are wrong.

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Sample questions with answers and explanations

Sample 1

Organisms that eat plants only are called _____.

Answer: B

Herbivores eat ONLY plants. The prefix 'herbi-' comes from Latin 'herba' (plant/herb), and '-vore' means 'eater.' Examples: cows, deer, rabbits.

Why the other choices are wrong
  • A. 'Ovipores' is not a real biological term. 'Oviparous' means egg-laying, which is unrelated to diet.
  • C. Omnivores eat BOTH plants and animals — 'omni' means 'all.' Examples: humans, pigs, bears.
  • D. Carnivores eat ONLY meat/animals — 'carni' means 'flesh.' Examples: lions, sharks, eagles.

Sample 2

Vascular tissue that transports water in leaves connects directly to which of the following?

Answer: D

Plants have a built-in 'water highway' called xylem. Water enters through the roots, travels UP through the xylem in the stem, and into the leaves. The xylem inside the leaf is just a continuation of the same xylem in the stem — they connect like one long pipe.

Tip: Xylem = water UP. Phloem = food DOWN. The vascular system runs root → stem → leaf in one continuous pipe.

Why the other choices are wrong
  • A. Meristems are growing tissues at root tips — they don't transport water, they make new cells.
  • B. Pistils are flower parts (for reproduction), not water transport.
  • C. Root hairs ABSORB water from soil — but they're far from the leaves. The water still has to travel through the stem xylem first.

Sample 3

Which of the following statements is not true of energy in the biosphere?

Answer: C

FALSE: Energy does NOT cycle in ecosystems — it FLOWS one-way (sun → producers → consumers → lost as heat). What CYCLES is matter (carbon, water, nitrogen). The classic ecology rule: 'Energy flows, matter cycles.' So C is the false statement (the answer to a 'NOT TRUE' question).

Tip: MEMORIZE: 'Energy flows, matter cycles.' This is THE ecology rule. Any option saying 'energy cycles' is wrong.

Why the other choices are wrong
  • A. TRUE — energy flow is one-directional (sun → ecosystem → heat lost).
  • B. TRUE — energy is conserved overall (1st law of thermodynamics), even as it transforms.
  • D. TRUE — energy ultimately leaves as heat (waste energy from metabolism).
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