Jin,

For homework on 9/3/2013, please do the following in preparation for the lesson on 9/4/2013.

Step 1:  Please download this audio program for your computer:

http://audacity.sourceforge.net/download/

Step 2:  Listen to the attached audio clip

Step 3:  Answer questions about the audio clip

Questions:

1.  What is the main topic of the talk?

2.  Listen to part of the lecture again, and answer the question.  Why does the professor say this..."nine months of winter and temperatures plummeting to as low as minus 55 degrees celsius?"

3.  What can be inferred about the arctic tundra from the passage?

4.  According to the lecture how does snow help tundra plants to survive?

5.  Why does the professor talk about crowds of people?

6.  Match the characteristic for each plant, for each characteristic place of check mark in the correct plant column.

Labrador Tea Saxifrage  Marsh Marigold

- Has hairy leaves

- Grows in clumps

- Flowers follow the sun

- Grows close to the ground

[Lesson Credits:  Listening Building MP3 TOEFL, Track 1]

Science

W:  Okay everyone, picture this:  nine months of winter and temperatures plummeting to as low as minus 55 degrees Celsius.  These are the types of conditions found in the Arctic tundra. It doesn’t sound very appealing for plant life, does it? Yet plants do manage to survive in this harsh environment. How do they do it? Tundra plants have developed several unique adaptations to enable them to live in their Arctic surroundings.

One adaptation of tundra plants is that they grow close to the ground. The majority of them only grow between 5 and 20 centimeters in height. This is important because plants that are closer to the ground are able to stay warmer. In the spring, the ground absorbs and retains the heat from the sun. By growing only a few centimeters in height, tundra plants can soak up this heat from the ground below. Then in the winter, a thick blanket of snow helps to protect the plants from the cold air above.

Another way these plants have adapted to their cold environment is to grow in clumps. A good example of this is the Labrador tea plant. The flowers and leaves of this plant grow close together to preserve warmth. It’s sort of like what happens with crowds of people. Have you ever noticed that crowded rooms always seem to be hotter? This is because the combined body warmth generates higher temperatures. The same thing happens with tundra plants. The closer they grow to one another, the warmer they stay. In fact, it’s been found that plants growing in clumps are 20 degrees warmer than the surrounding air.

Finally, the leaves and flowers of tundra plants have developed additional ways to capture warmth and sunlight. For instance, the leaves of the saxifrage plant are covered in tiny white hairs to keep the plant warm. My personal favorite is the marsh marigold plant whose flowers actually follow the sun and direct light and warmth toward the pollen areas of the flower. These warm areas are then better able to attract pollinators like insects, increasing the plant’s reproductive success.