Question 49
IGCSE_MODEL_QUESTIONS_VOL1
•
2020
•
ENGLISH_LANGUAGE
•
objective
Explain how photosynthesis works to a younger sibling who has never studied science before. Write an expository passage of 150‑200 words that describes the process in simple language, uses cause‑and‑effect linking words, and includes the main stages (light‑dependent reactions and the Calvin cycle).
Answer Options
A.
Photosynthesis is the process plants use to turn sunlight into food. First, in the light‑dependent reactions, chlorophyll absorbs heat and splits carbon dioxide into oxygen and carbon monoxide. The oxygen is stored in the leaves while the carbon monoxide is used to make a molecule called NADH. Then, in the Calvin cycle, the plant combines NADH with water to create glucose. Because the plant creates oxygen, it helps the environment.
B.
Photosynthesis lets plants make food by using sunlight. In the first stage, called the Calvin cycle, the plant captures sunlight with chlorophyll and produces ATP. The ATP then powers the light‑dependent reactions, which turn water into carbon dioxide and glucose. The oxygen released comes from the breakdown of glucose. This process supplies the plant with energy.
Correct Answer
C.
Photosynthesis is the way green plants make their own food using sunlight. First, in the light‑dependent reactions, the leaves capture sunlight with a green pigment called chlorophyll. The light energy splits water molecules into oxygen and hydrogen, and the oxygen is released into the air while the hydrogen helps create a special energy carrier called ATP. Then, in the Calvin cycle, the plant uses the ATP and carbon dioxide from the air to build a sugar called glucose, which the plant uses for growth and energy. Because the plant turns light into food, it also produces the oxygen we breathe, making photosynthesis essential for all living things.
D.
Photosynthesis is how plants turn soil nutrients into sugar. Sunlight is not involved; instead, plants absorb carbon dioxide and convert it directly into glucose using enzymes in the roots. The reaction releases oxygen as a by‑product. The light‑dependent reactions and the Calvin cycle are actually parts of cellular respiration, not photosynthesis.
Correct Answer
C
Correct Option:
Photosynthesis is the way green plants make their own food using sunlight. First, in the light‑dependent reactions, the leaves capture sunlight with a green pigment called chlorophyll. The light energy splits water molecules into oxygen and hydrogen, and the oxygen is released into the air while the hydrogen helps create a special energy carrier called ATP. Then, in the Calvin cycle, the plant uses the ATP and carbon dioxide from the air to build a sugar called glucose, which the plant uses for growth and energy. Because the plant turns light into food, it also produces the oxygen we breathe, making photosynthesis essential for all living things.
About This Question
This is
Igcse Model Questions Vol1
2020
English Language
Question 49.
It is one of the
objective
questions from the
2020
Igcse Model Questions Vol1
English Language
examination.
Difficulty level:
Medium
.