Why do Zebras have stripes? Scientists claim to have the answer

With the collaboration of the students of 2º Bachibac 

IES Alberto Pico (Santander)

Wearing striped clothing could help protect holidaymakers from mosquito bites, scientists have found after solving the mystery of why zebras are black and white.

It is a question which has plagued biologists for centuries but now a team from the University of California, Davis, believe zebras’ unusual monochrome markings evolved in order to repel biting insects, such as horseflies and tsetse flies, which tend to avoid striped surfaces. And the findings could help humans cut their risk of being bitten by donning stripy T-shirts, although scientists cautioned that the type of striped surface and material used may alter its effectiveness.

“A T-shirt may help somewhat but it might not be the whole story. Certainly if you are going to buy a T-shirt make sure the stripes are thin,” Tim Caro, lead author and UC Davis professor of wildlife biology said. “Don’t buy a striped jumper too quickly. Black and white striped surfaces reflect different sorts of visible light but they also reflect different sorts of polarised light which we can’t see but flies can. “The extent of polarised light reflected also depends on the nature of the surface – think of gloss and matte paint – and hairs probably reflect polarised light in different ways. “So it may be that the different hairs of the zebra’s pelt are important in preventing flies from landing on them.”

Varying explanations for zebra stripes, which have been proposed since Alfred Russel Wallace and Charles Darwin debated the problem 120 years ago, have included a form of camouflage, assisting escape from predators by visually confusing them, heat management or some kind of social function.

The study, published in the journal Nature Communications, mapped the geographic spread of seven different species of zebras, horses and asses and their subspecies and recorded the thickness, location and intensity of their stripes on several parts of the body. It compared the animals’ geographic reach with other variables such as woodland habitats, the range of predators, temperatures and the numbers of ectoparasites such as tsetse flies. After examining where the striped animals and variables overlapped the scientists ruled out all but one of the existing explanations, that of avoiding blood sucking flies.

"No one knew why zebras have such striking colouration," Prof Caro said. "But solving evolutionary conundrums increases our knowledge of the natural world and may spark greater commitment to conserving it." According to Prof Caro it is not yet known why biting flies avoid striped surfaces. He said: “Some ideas include lateral inhibition but these are not researched as yet.”

Question 1: [2 POINTS] Indicate whether the following statements are TRUE or FALSE and write down the sentences or part of the text that justifies your answer. No points will be given if the evidence is not correct.

 

a)    It has never been an interesting question why zebras are white and black.

b)    Wearing a striped T-shirt prevents you from being bitten by insects.

c)     The explanation for zebra stripes had been proposed a long time ago.

d)    One reason about zebra stripes could be a way to control their temperature.

e)    The study has shown that it is probably that the aim of stripes is to avoid flies.

f)      According to Prof Caro, solving evolution mysteries is pointless.

g)    We know for sure why biting flies avoid striped surfaces.

Question 2: [2 POINTS] Choose and answer only TWO of the following questions in your own words according to the text.

a)    According to Davis, why do zebras have stripes?

b)    Why aren’t zebras bitten by insects?

c)     What can flies see in black and white striped surfaces but humans cannot?

d)    Which comparations were done among the different species of zebras, horses and asses?

e)    Why do zebras have such striking colouration?

 

Question 3: [1,5 POINTS] Find words or phrases in the text that correspond to the words and definitions given. You only need to have five correct answers to get 1,5 points.

a)    Disturb (paragraph 2) 

b)    Hold back (paragraph 2)

c)     Modify (paragraph 2)

d)    Complete (paragraph 3)

e)    Sweater, pullover (paragraph 3)

f)      Issue (paragraph 4)

g)    Help (paragraph 4)

h)    Mystery (paragraph 6)

i)      Dedication (paragraph 6)

 

Question 4: [1,5 ] Choose the correct option – a, b, c or d – for each question and COPY both the letter and the sentence that follows onto your answer sheet.

1. Biting flies avoid …
1. any stripy T-shirts.
2. zebras’ pelt
3. white and black surfaces
4. thin stripes
2. Black and white striped surfaces reflect …
1. all sorts of light
2. different sorts of visible and polarized light
3. visible light that we cannot see but flies can.
4. only polarized light.
3. The explanation given for the stripes of zebras after the study published in the journal Nature Communications is that …
1. it is a kind of social function.
2. it is a form of repelling flies.
3. it protects them from predators.
4. it doesn’t give any clear explanation

 

Written production (3 points)

Write a short essay (120 – 150 words) on the following topic. Essays up to 200 words will not be penalized.

“Zoos should be banned since animals should live in the wild”. Do you agree with this statement?

                                        

Key

Question 1: [2 POINTS] Indicate whether the following statements are TRUE or FALSE and write down the sentences or part of the text that justifies your answer. No points will be given if the evidence is not correct.

a)    It has never been an interesting question why zebras are white and black.

(p 2) False It is a question which has plagued biologists for centuries

b)    Wearing a striped T-shirt prevents you from being bitten by insects.

(p 3) False A T-shirt may help somewhat but it might not be the whole story

c)     The explanation for zebra stripes had been proposed a long time ago.

(p 4) True explanations for zebra stripes, which have been proposed since Alfred Russel Wallace and Charles Darwin debated the problem 120 years ago.

d)    One reason about zebra stripes could be a way to control their temperature.

(p 4) True have included a form of camouflage, assisting escape from predators by visually confusing them, heat management

e)    The study has shown that it is probably that the aim of stripes is to avoid flies.

(p5) True the scientists ruled out all but one of the existing explanations, that of avoiding blood sucking flies.

f)      According to Prof Caro, solving evolution mysteries is pointless.

(p 6) False But solving evolutionary conundrums increases our knowledge of the natural world and may spark greater commitment to conserving it.

g)    We know for sure why biting flies avoid striped surfaces.

(p 6)  False it is not yet known why biting flies avoid striped surfaces

 

Question 2: [2 POINTS] Choose and answer only TWO of the following questions in your own words according to the text.

a)    According to Davis, why do zebras have stripes?

(p2)They have them because they are an evolution change which allows zebras to repel insects that always try to avoid striped surfaces.

b)    Why aren’t zebras bitten by insects?

(p3) Insects tend to avoid striped surfaces; however, black and white surfaces reflect different sorts of polarised light which can only be seen by them, so it may be that the different hairs of zebra’s pelt are important in preventing flies from landing on them.

c)     What can flies see in black and white striped surfaces but humans cannot?

(p3) different sorts of polarised light

d)    Which comparations were done among the different species of zebras, horses and asses?

(p5)The study compares the natural place of the animals with factors like the kind of habitat, other dangerous species, the temperature and parasites such as tsetse flies.

e)    Why do zebras have such striking colouration?

(p 6) It isn’t known yet,

 

Question 3: [1,5 POINTS] Find words or phrases in the text that correspond to the words and definitions given. You only need to have five correct answers to get 1,5 points.

a)    Disturb (paragraph 2)                 plagued

b)    Hold back (paragraph 2)            repel

c)     Modify (paragraph 2)                 alter

d)    Complete (paragraph 3)             whole

e)    Sweater, pullover (paragraph 3) jumper

f)      Issue (paragraph 4)                   problem

g)    Help (paragraph 4)                    assisting

h)    Mystery (paragraph 6)               conundrum

i)      Dedication (paragraph 6)           commitment

 

Question 4: [1,5 ] Choose the correct option – a, b, c or d – for each question and COPY both the letter and the sentence that follows onto your answer sheet.

 Biting flies avoid …

1. any stripy T-shirts.
2. zebras’ pelt
3. white and black surfaces
4. thin stripes
1. Black and white striped surfaces reflect …
1. all sorts of light
2. different sorts of visible and polarized light
3. visible light that we cannot see but flies can.
4. only polarized light.
2. The explanation given for the stripes of zebras after the study published in the journal Nature Communications is that …
1. it is a kind of social function.
2. it is a form of repelling flies.
3. it protects them from predators.
4. it doesn’t give any cleat explanation

 

English - Pubs (A1-A2 - with subtitles)

Watch the video and answer the questions below:

• 1.       When did the first pub open?
• 2.       Where did it open?
• 3.       What does “pub” stand for?
• 4.       What can people do in a pub?
• 5.       Why may a pub lose the licence they need to sell alcohol?
• 6.       Which drinks do pubs usually sell?
• 7.       Which name is given to red beer?
•        …and to cold blonde beer?
•        …and to thick black beer?
• 8.   What two examples of typical British food are given?
• 9.   How much is an average main dish?
• 10.   When was smoking prohibited in pubs?

 

KEY

• 1.       1000 years ago
• 2.       St Albans in north London
• 3.       Public house
• 4.       Meet, drink and chat
• 5.       If they sell alcohol to under 18s
• 6.       Wine, soft drinks and beer
• 7.       Bitter or ale
• .       Lager
• .       Stout or Guinness
• 8.   Fish and chips and sausages and mash
• 9.   £5 to £10
• 10.   On July 2017

Gap filling

You advertised in a magazine for an English-speaking pen friend. Here is one of the replies you received.

 Complete gaps with 

 a. about      b.at        c.away      d.fairly    e.for      f.in 

g.quite     h.really      i.to        j up    k.with      l.in

I am replying 1____ your advert for a penfriend. You’d probably like to know something 2 _____me, so here goes!!!

I’m nineteen and live 3____ Salisbury. I left school two years ago, did a secretarial course and now work in a 4____ large company. My job is 5____

Varied, and I’ve made some 6____ good friends at work. I usually go 7____ some of them for a pub lunch. Are you still at school or have you got a job?

          In the evenings and at the weekends, I usually go dancing or to the cinema. What do you do 8____ your spare time? I’m not very good 9____ sports, except swimming. Do you do any sports?

          I live with my parents and brother. He’s younger than me and still at school. His exams are only a few weeks 10_____ (poor thing!). Have yoy got any brothers or sisters?

          Salisbury is famous for its cathedral, of course, but it’s also very good 11_______ shopping. Please tell me something about the place where you live.

          Next time I write, I’ll send you a photo of my family. Do you think you’ll ever come to England? It would be nice to meet 12_____ sometime.

KEY

 

1. i

2. a

3. f/l

4. d

5. g

6. h

7. k

8. f/l

9. b

10. c

11. e

12. j

You See Pepsi, I See Coke: New Tricks for Product Placement

The streaming services have data on viewers’ spending habits and brand preferences, and they’re looking into new ways to use it.

First came product placement. In exchange for a payment, whether in cash, supplies or services, a TV show or a film would prominently display a brand-name product.

Then there was virtual product placement. Products or logos would be inserted into a show during editing, thanks to computer-generated imagery.

Now, with the rise of Netflix and other streaming platforms, the practice of working brands into shows and films is likely to get more sophisticated. In the near future, according to marketing executives who have had discussions with streaming companies, the products that appear onscreen may depend on who is watching.

In other words, a viewer known to be a whiskey drinker could see a billboard for a liquor brand in the background of a scene, while a teetotaller watching the same scene might see a billboard for a fizzy water company.

Streaming services could also drop in brand-name products based on when a show is being watched. Someone who watches a streaming show in the morning could see a carton of orange juice within a character’s reach, while a different viewer watching the same thing in the afternoon could see a can of soda.

It could start within a year, said Stephan Beringer, the chief executive of Mirriad, a virtual product placement company that has worked brands including Pepsi, Geico and Sherwin-Williams into ABC’s “Modern Family,” CBS’s “How I Met Your Mother” and the Univision program “El Dragón.”

Streaming services are more likely than traditional TV companies to pull off this specially targeted version of product placement because they have direct access to far more information on their customers. With every click of the remote, viewers tell the services something about themselves, information that can be used to determine which products might appeal to them.

This supercharged version of digital product placement is being developed at a time when the marketing business — which bet big on TV commercials for decades — needs new tricks to grab the attention of ad-hating and cord-cutters.

Mr. Beringer, the head of Mirriad, said the current digital product placement technology has been successful enough to suggest that a bespoke version is a logical next step.

Question 1. Indicate whether the following statements are TRUE or FALSE and write down which part of the text justifies your answer

• 1.    Product placement involves showing brand-name products on a TV programme or film without charge.
• 2.  The rise of streaming platforms may affect the practice of working brands on TV and the cinema.
• 3.    Pretty soon, the products we see onscreen will be different for different types of viewers.
• 4.    TV companies have better access to information about their viewers than streaming services.

Question 3: Find words or phrases in the text that mean the same as the following.

• a)    Show. Make viewable. (paragraph 2)
• b)    Person who does not drink alcohol. (paragraph 5)
• c)    Metal container (paragraph 6)
• d)    Succeed in doing (paragraph 8)
• e)    Appeal (paragraph 9)

 

KEY

Question 1:

1.    False. In exchange for a payment, whether in cash, supplies or services, a TV show or a film would prominently display a brand-name product.

2.    True. with the rise of Netflix and other streaming platforms, the practice of working brands into shows and films is likely to get more sophisticated.

3.    True. In the near future, according to marketing executives who have had discussions with streaming companies, the products that appear onscreen may depend on who is watching.

4.   False. Streaming services are more likely than traditional TV companies to pull off this specially targeted version of product placement because they have direct access to far more information on their customers.

Question 3:

• a)    Display
• b)    Teetotaller
• c)    Can
• d)    Pull off
• e)    Grab the attention