Question

It is easy for us to tell who our family members are, but do plants recognize their own family? Some do, scientists say, according to a report by Science News in early 2010.

Guillermo P. Murphy and Susan Dudley are two plant scientists from McMaster University in Hamilton, Canada. They did a few experiments with Jewelweeds, a kind of flower that grows in wet, shady spots. They found that the flowers seem to know their own flower family. In their experiments, Murphy and Dudley planted jewelweeds in pots with either siblings (同属) or strangers.

When jewelweeds were planted in pots with strangers, the plants started to grow more leaves than if they had been planted alone. This response suggests that plants are competing with strangers for sunlight, since a plant with more leaves can receive more light and make more food. Jewelweeds normally grow in the shade, where sunlight is scarce.

When jewelweed seedlings were planted with siblings, they grew a few more branches than they normally would if they were alone – but they did not start growing lots of extra leaves. This behavior suggests the plants are more likely to share resources, rather than compete.

According to the Science News report, Jewelweeds are not the first plants that plant scientists have studied for family recognition. In 2007, Dudley and her team studied the Great Lakes sea rocket, a plant that grows on the beach – where it may be hard to get fresh water. In that experiment, the scientists observed that when sea rockets were planted with siblings, they tolerated each other. But when they were planted with strangers, the sea rockets reacted by working extra hard to grow lots of roots. 

Dudley says this behavior makes sense because sea rockets, on the beach, get plenty of sun but struggle for water – so when they’re threatened, they compete for water. Jewelweeds have plenty of water but have to compete for sunshine, so they grow more leaves.

52. When the McMaster University scientists experimented with Jewelweeds, they __________.

A. planted Jewelweeds alone               

B. separated jewelweeds from their siblings

C. planted Jewelweeds in an unusual environment

D. grew jewelweeds together with either family or strangers

53. Which of the following shows that Jewelweeds compete with others?

A. Jewelweeds grow extra leaves.

B. Jewelweeds grow more branches as well as extra leaves.

C. Jewelweeds grow more branches rather than more leaves.

D. Jewelweeds grow taller than usual.

54. The underlined word “scarce” in paragraph 3 means _____________.

   A. dark            B. not enough         C. not available          D. mild

55. From the text, we can conclude that the Great Lakes sea rockets ____________.

A. prove the same point as Jewelweeds       B. compete with strangers for sunlight

C. cannot recognize their siblings            D. grow more leaves when planted with strangers

56. What is the article mainly about?

A. New discoveries about plants.             B. How plants compete with each other.

C. Family recognition among plants.          D. Jewelweeds and the Great Lakes sea rockets.

Answer 1

52-56 DABAC