CD1-track20

Biology: Sunshine

1. What is the main idea of the lecture?

A The lack of Vitamin D is the main cause of skin cancer.

B Sunbathing for a long time causes no problems.

C The danger of the sunshine has been ignored because of its benefits.

D The advantages and disadvantages of the sun .

(D)

2. According to the lecture, when concerned with our bodies, what is the main

function of sunshine?

A It changes ergosterol to Vitamin D.

B It suppresses serotonin.

C It can cause Seasonal Affective Disorder.

D It can cause skin and bladder cancer.

(A)

听力原文：

CD1-track20

Biology: Sunshine

“Good morning class. Today I thought we would talk about something bright and

cheerful: the sun. I know most of you got to school before the sun came up, but can

anyone tell me how they feel when its sunny compared to when it’s cloudy?”

(Another voice)

“I find it’s a lot easier to get up in the morning if it’s sunny”

(Back to narrator)

“Good. How do you usually feel if it’s cloudy?”

(Another voice)

“Well I don’t mind, because I enjoy staying in on a rainy day curled up in bed with a

good book.”

(Back to narrator)

“Well, what if I told you it would rain for weeks on end with no break?”

(Another voice)

“Ya I can see your point. I don’t think I would like that very much”

(Back to narrator)

“Most of the articles we read lately regarding the sun are discussing the negative

effects of staying in the sun for too long saying that ultra violet radiation from the sun

is a major cause of skin cancer. Although these articles are factual, the sun does have

some positive side effects as well. As a matter of fact some scientists believe that

sunlight may reduce the risk of several types of cancer. “

(Another voice)

“Excuse me but many articles I’ve read blame the sun for causing cancer, stating that

it can take as little as 30min to get a sunburn”

(Back to narrator)

“Yes and those articles are correct. However in small doses the sun can be quite

healthy for you. In fact recent studies have found that sunlight can actually help

protect you from certain types of cancer such as breast colon bladder and stomach.

More importantly the sun provides us with our main source of vitamin D.”

(Another voice)

“Well I don’t need to worry about vitamins because I take multi vitamins everyday”

(Back to narrator)

“That’s great, but wouldn’t it be better if you didn’t have to take them and you were

able to get vitamins in a more natural way such as food and the sun? Most people

understand that nutrients strengthen our bones and muscles and heighten our immune

system to better fight diseases like the common cold. However, many people don’t

realize that the ultra violet or UV rays from the sun actually convert irgasterol which

is found in our skin to vitamin D. Vitamin D is needed for normal growth of teeth and

bones and has also been proven to prevent the development and increase of cancerous

tumors”

(Another voice)

“Does that mean we should spend all the day in the sun without any protection?

(Back to narrator)

“No spending roughly 10min per day in the sun should be enough to supply us with

all the Vitamin D that we need.”

(Another voice)

“What happens if we don’t get enough Vitamin D?”

(Back to narrator)

“Excellent question! I’m glad you asked me that. Low Vitamin D can cause many

diseases such as chronic fatigue, a softening of the bones, osteoporosis and multiple

skilerriosis. Getting back to our mood some researchers have proven that sunshine

can actually cheer you up. When I see the sun I always feel happy energetic and

generally positive. But did you realize that the sun can change your mood chemically

and might even prevent depression. There is a saying called ‘spring fever’ when many

people feel the beginning of spring as a sign of good days ahead. During the winter

many of us are stuck indoors out of the sun. The lack of sun causes for many people a

condition called SAD or Seasonal Affective Disorder. SAD is caused by suppression of

serotonin which keeps our mood, emotions, sleep and appetite in check. When we

don’t get enough we feel depressed and this is usually experienced by people who are

deprived of sunlight during the dull winter months. So class during your break why

don’t you step outside and get a bit of Vitamin D?”