Algae is a primitive form of life, a single-celled or simple multiple-celled organism that is able to conduct the process of photosynthesis. It is generally found in water but can also be found elsewhere, growing on such surfaces as rocks or trees. The various types of algae are classified according to pigment.

Blue-green algae, or Cyanophyta, can grow at very high temperatures and under high- intensity light. This type of algae is the oldest form of life with photosynthetic capabilities. Fossilized remains of blue-green algae more than 3.4 billion years old have been found in parts of Africa.

Green algae, or Chlorophyta, is generally found in fresh water. It reproduces on the surfaces of enclosed bodies of water such as ponds or lakes and has the appearance of a fuzzy green coating on the surface of the water.

Brown algae, or Phaeophyta, grows in shallow, temperate water. This type of algae is the largest in size and is most recognizable as a type of seaweed. Its long stalks can be enmeshed on the ocean floor, or it can float freely on the ocean's surface.

Red algae, or Rhodophyta, is a small, delicate organism found in the deep waters of the subtropics. This type of algae has an essential role in the formation of coral reefs: it secretes lime from the seawater to foster the formation of limestone deposits.

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions

What is the author's main purpose?

Câu hỏi liên quan

• The phrase “these years” in the third paragraph refers to ________.

• Where in the passage is the name of Pippin’s hometown mentioned?

• Which of the followings is not mentioned as part of the “new media”?

ZUNIA12

• What can we assume is NOT true about Middle Earth?

• The word “pseudonym” in the passage refers to ___________.

• Based on the passage, what is probably true about the south of France?

• According to the article the Feingold diet is NOT ___________.

• What happens to nitrogen in body tissues if a diver ascends too quickly?

• Nowadays the common method for drying vegetables and minced meat is ______.

• The word ‘akin’ in paragraph 1 could be best replaced by ...........

• The author of this passage is most likely __________________ .

• The author mentions all of the following as concerns of telecommuting, EXCEPT ...........

•  According to the passage, the benefit of listening to music while learning and studying is that it ..............

• The word “splendors” in the passage could be best replaced by which of the following?

• Which of the following is mentioned as the main cause of the destruction of Mantle’s body?

• How did Juliette Davidson benefit from the experience of her first job?

• According to the passage 3, Pilobolus fungus___________

• The word “odd” refers to which of the following?

• According to the passage, the difficulty in diagnosing allergies to foods is due to ______________.

• During the 1860’s, canned food products were _________ .