Beranda › Semua Latihan

Latihan TOEFL Reading 4: C4 Photosynthesis

Baca passage berikut dengan teliti, lalu kerjakan 15 soalnya. Jawaban dan pembahasan bisa dibuka setelah kamu mencoba sendiri.

Most plants use a process called C3 photosynthesis, in which carbon dioxide is captured directly by an enzyme that also reacts with oxygen, wasting energy through a process known as photorespiration. In hot, dry climates, this inefficiency becomes a serious disadvantage, since plants must keep their leaf pores open longer to gather enough carbon dioxide, losing more water to evaporation in the process.

Some plants, including corn and sugarcane, have evolved an alternative pathway known as C4 photosynthesis. In these plants, carbon dioxide is first captured by a different enzyme and converted into a four-carbon compound before being shuttled to specialized cells deeper in the leaf, where it is concentrated for the main photosynthetic reactions. This extra step allows C4 plants to keep their leaf pores open for shorter periods, conserving water while still capturing enough carbon dioxide.

Because of this efficiency, C4 plants generally outperform C3 plants in hot, sunny, and dry environments, though they require more energy to build the additional enzymes involved. As climate patterns shift toward more extreme heat in some agricultural regions, researchers have shown growing interest in transferring C4 traits into staple C3 crops such as rice, in hopes of improving yields under future growing conditions.

Soal

1. What is the passage primarily about?

  1. How corn is grown commercially
  2. The history of the discovery of photosynthesis
  3. The role of oxygen in plant respiration alone
  4. A comparison of C3 and C4 photosynthesis and why C4 is more efficient in heat
Lihat jawaban dan pembahasan

Jawaban: D. A comparison of C3 and C4 photosynthesis and why C4 is more efficient in heat

Passage membandingkan efisiensi C3 dan C4, terutama di iklim panas — ini alur utamanya dari awal sampai akhir.

2. The word 'inefficiency' in paragraph 1 is closest in meaning to

  1. growth
  2. moisture
  3. speed
  4. waste
Lihat jawaban dan pembahasan

Jawaban: D. waste

'Inefficiency' merujuk pada energi yang terbuang lewat photorespiration — 'waste' adalah sinonim terdekat.

3. According to the passage, why must C3 plants keep leaf pores open longer in hot, dry climates?

  1. To absorb more sunlight
  2. To cool the leaf surface
  3. To gather enough carbon dioxide due to less efficient capture
  4. To release excess oxygen
Lihat jawaban dan pembahasan

Jawaban: C. To gather enough carbon dioxide due to less efficient capture

Teks menyebut C3 plants 'must keep their leaf pores open longer to gather enough carbon dioxide' karena proses penangkapan CO2-nya kurang efisien.

4. What can be inferred about C4 plants?

  1. They use no water at all
  2. They cannot be found in food crops
  3. They require more energy to build extra enzymes but conserve water in heat
  4. They only grow in shaded environments
Lihat jawaban dan pembahasan

Jawaban: C. They require more energy to build extra enzymes but conserve water in heat

Paragraf 3 menyebut C4 plants 'require more energy to build the additional enzymes' namun tetap unggul di iklim panas/kering karena hemat air.

5. Why does the author mention rice in the final paragraph?

  1. To give an example of ongoing research applying C4 traits to improve crop yields
  2. To show rice is naturally a C4 plant
  3. To compare rice with corn's water needs
  4. To argue rice should not be grown in hot climates
Lihat jawaban dan pembahasan

Jawaban: A. To give an example of ongoing research applying C4 traits to improve crop yields

Kalimat terakhir menyebut peneliti tertarik 'transferring C4 traits into staple C3 crops such as rice' — rice adalah contoh aplikasi riset.

6. The word 'pathway' in paragraph 2 is closest in meaning to

  1. a biological process or route
  2. a walking trail
  3. a chemical byproduct
  4. a type of leaf
Lihat jawaban dan pembahasan

Jawaban: A. a biological process or route

'C4 photosynthesis pathway' merujuk pada jalur/proses biologis tertentu, bukan jalan fisik.

7. According to paragraph 1, what does photorespiration waste?

  1. Energy
  2. Soil nutrients
  3. Water only
  4. Sunlight
Lihat jawaban dan pembahasan

Jawaban: A. Energy

Disebutkan photorespiration 'wasting energy' sebagai efek dari proses C3 yang kurang efisien.

8. According to paragraph 2, where is carbon dioxide concentrated in C4 plants?

  1. In the roots
  2. In specialized cells deeper in the leaf
  3. In the stem only
  4. On the leaf surface
Lihat jawaban dan pembahasan

Jawaban: B. In specialized cells deeper in the leaf

Disebutkan CO2 'shuttled to specialized cells deeper in the leaf, where it is concentrated'.

9. It can be inferred that C3 plants lose more water than C4 plants in hot climates because

  1. They must keep leaf pores open longer to gather enough carbon dioxide
  2. They lack roots
  3. They grow taller
  4. They have larger leaves
Lihat jawaban dan pembahasan

Jawaban: A. They must keep leaf pores open longer to gather enough carbon dioxide

Paragraf 1 menyebut C3 plants 'must keep their leaf pores open longer' sehingga lebih banyak air menguap.

10. Why does the author explain the C3 process in paragraph 1 before describing C4 in paragraph 2?

  1. To provide a baseline for comparison that highlights C4's advantages
  2. To criticize scientific classification systems
  3. To introduce an unrelated topic
  4. To argue C3 plants are superior
Lihat jawaban dan pembahasan

Jawaban: A. To provide a baseline for comparison that highlights C4's advantages

Urutan penjelasan ini membangun perbandingan yang menonjolkan keunggulan C4 di iklim panas.

11. The word 'staple' in paragraph 3 (staple C3 crops) is closest in meaning to

  1. a rare specialty crop
  2. a farming tool
  3. a primary or essential food crop
  4. a type of fertilizer
Lihat jawaban dan pembahasan

Jawaban: C. a primary or essential food crop

'Staple crops' merujuk pada tanaman pangan pokok/utama seperti padi.

12. According to paragraph 3, which two plants are given as examples of C4 plants?

  1. Wheat and rice
  2. Oats and barley
  3. Potatoes and tomatoes
  4. Corn and sugarcane
Lihat jawaban dan pembahasan

Jawaban: D. Corn and sugarcane

Disebutkan eksplisit 'plants, including corn and sugarcane, have evolved' jalur C4.

13. What do C4 plants require more of compared to C3 plants?

  1. Soil acidity
  2. Sunlight exposure
  3. Water for growth
  4. Energy to build additional enzymes
Lihat jawaban dan pembahasan

Jawaban: D. Energy to build additional enzymes

Disebutkan C4 plants 'require more energy to build the additional enzymes involved'.

14. It can be inferred that researchers are interested in giving rice C4 traits in order to

  1. Eliminate its need for sunlight
  2. Make it grow underwater
  3. Improve its yield under hot growing conditions
  4. Change its color
Lihat jawaban dan pembahasan

Jawaban: C. Improve its yield under hot growing conditions

Tujuan riset disebut 'improving yields under future growing conditions' yang makin panas.

15. What is paragraph 2 mainly about?

  1. How the C4 photosynthetic pathway works mechanically
  2. Global crop trade patterns
  3. The history of rice cultivation
  4. The chemistry of photorespiration
Lihat jawaban dan pembahasan

Jawaban: A. How the C4 photosynthetic pathway works mechanically

Paragraf 2 menjelaskan mekanisme kerja jalur C4 secara rinci, bukan sejarah atau perdagangan.

Latihan interaktif di app

Lihat semua latihan lainnya