Extra. Unit 10. Can humans really feel temperature?

Answer the questions and write a summary.

Extra. Unit 4. Welwitschia. One Ugly Plant?

One Ugly Plant!

Welwitschias live in the coastal desert regions of Namibia and Angola, Africa. They get the moisture they need to survive from fog rolling in from the ocean. Carbon-14 dating has placed the age of two of the plants at 1,500-years-plus!

“It's a fascinating plant because it is so bizarre,” says Judy Jernstedt, a plant morphologist at the University of California who has traveled halfway around the world to see them. “Basically, Welwitschia has only two ratty-looking leaves that last hundreds if not thousands of years.”

The stem of an adult plant is a look-alike for an upside-down traffic cone. From it, two long, straplike leaves grow and grow and never fall off. As the centuries pass, the desert winds whip, shred, and tangle them into a shoulder-high mass of twisted ribbons. An African name for the plant says it all: “long-haired thing.” Named after Friedrich Welwitsch, the explorer, Welwitschia, bears small cones instead of flowers. Its male and female organs are separated. Where in the scheme of plants does it belong?

And there is another mystery. Desert plants grow with little or no water. They can't seal their tissues completely to hold what little there is, because they need to take in carbon dioxide for photosynthesis. As a result, most have no leaves, or tiny ones. Welwitschia's leaves spread a quarter of a meter and release a liter of water a day! Botanists think it must come from the plant's collection of soil moisture.

A female plant produces some 20,000 seeds each year. In a greenhouse they germinate freely, but in the desert 90 percent of them mold. The 10 percent that survive send down long taproots in just a few weeks.

“Welwitschia combines some traits of gymnosperms such as conifers and also traits of flowering plants, but it still isn't clear to plant biologists exactly where it fits into the emerging picture of plant evolution,” says Jernstedt. It has some Gymnosperm characters shared with conifers like Pinus and Thuja, but some Angiosperm characters – like wood vessels in the secondary xylem – as well. Welwitschia is not only pollinated by wind (like the gymnosperms) but also by insects. Both the female and male flowers produce nectar; the male flowers produce small quantities of pollen. Both characters are typical of insect-pollinated angiosperms . The male flowers are similar to some Angiosperm flowers . Pictures

Vocabulary

• carbon-14 dating: Determining the age of an ancient specimen by the amount of carbon-14 it contains.
• morphologist: A biologist who deals with the form and the structure of organisms, without consideration of function.

Activity

1. What makes this plant so weird, peculiar, wonderful, strange, bizarre, fascinating, misterious, and of course, unique? (list all the facts)
   
2. What characteristics does it share with gymnosperms and what treats are of angyomsperms?
   
3. The Welwitschia mirabilis has attracted a lot of attention from botanists since it was discovered in 1863. Why do you think scientists study plants? What potential benefit might there be in studying a plant that has developed the ability to live for so long in a harsh climate? Write a paragraph explaining your opinion.

http://www.eduplace.com/kids/hmsc/5/a/cricket/cktcontent_5a2.shtml
http://www.interhomeopathy.org/welwitschia-mirabilis-duality-and-transformation

 

Extra. Unit 1.Animal Angles: Life Form X

Since cucumbers and sea cucumbers both get nutrition from the soil, why are cucumbers plants and sea cucumbers animals?

Welcome to taxonomy — the science of classifying living things. Many taxonomists (not all!) sort life forms into five major categories or kingdoms. According to them, kingdom Protista contains single-cell organisms with a nucleus.

Kingdom Monera contains single-cell organisms without a nucleus. Animals are life forms that belong to kingdom Animalia, from the Latin word for “breath” or “soul.” They have more than one cell and are heterotrophs, meaning that they are nourished by other life forms. Kingdom Fungi contains multi-celled, heterotrophic life forms, such as mushrooms, which absorb nutrition from decaying organisms. Genetic studies show that mushrooms are more like animals than plants. Life forms in kingdom Plantae are multi-celled autotrophs, meaning that they make their food. Plants are producers; animals and fungi are consumers.

In general, cucumbers are plants because they create nourishment from elements in the soil. Sea cucumbers are animals because they get nourishment from plants and animals in the sediment they swallow. Dirt is just their vehicle for dinner.

People have eaten cucumbers and sea cucumbers for centuries. Cucumbers were probably first cultivated in northern India. The part we eat is actually a fruit, like grapes or melons. Some sea cucumbers go to great lengths not to be eaten. They push their intestines out and “slime” attackers, and then regenerate new intestines. (Pretty gutsy! And disgusting!). Video

Here's a challenge for taxonomists: Are meat-eating plants such as Venus flytraps really animals? Carnivorous plants thrive when they digest an insect or a lizard now and then. But they can survive without meat, and they have other plant-like characteristics, so they are classified as plants.

Taxonomy can be taxing!

1. What is taxonomy?
   
2. Explain the sentence "Taxonomy can be taxing"
3. Why shouldn't you eat some huge sea cucumbers?
   
4. Do you agree or disagree with the way taxonomists have classified the Venus flytrap? Why or why not? Write down your answer.
5. You know about the five kingdoms used to classify organisms: monerans, protists, fungi, plants, and animals. Invent an organism that has characteristics from two of the different kingdoms, such as a Venus flytrap. Write a short paragraph describing your organism. Name the two kingdoms in which it could be classified. Describe how your organism gets or makes food, moves (or doesn't move), how big or small it is, and whether it lives in a colony or alone.

http://www.eduplace.com/kids/hmsc/5/a/cricket/cktcontent_5a13.shtml

Extra. Unit 2. Bacteria in guts.

Read the text and answer the questions (full sentences) in your notebook. 

If you do the activity, send me an email to let me know:
ana.gil@educa.madrid.org

 

Germs explain some animal behaviors

The way hyenas smell is no laughing matter. Kevin Theis has been known to empty a laboratory of fellow scientists just by opening a bottle of what he calls “hyena butter.”
Hyenas secrete the pasty substance from a pouch tucked under their tails. This so-called butter is seriously stinky. It’s also crucial to how these African mammals communicate, explains Theis. An ecologist, he studies animal behavior and microbiology at Michigan State University in East Lansing. (Behavior is how an animal reacts to a particular situation or stimulus.)

Hyenas rub their pungent paste onto grass stalks — a practice called scent marking. The smell of that musky paste is something only another hyena could love. In fact, hyenas eagerly sniff the secretions to identify one another. Scents are one of the many ways animals are known to trade information. Indeed, odors can share a host of important data. What scientists are just beginning to realize is that when hyenas use scents to communicate, it’s bacteria that do most of the “talking.”

Kevin Theis takes blood an Each spotted hyena has a different ratio of dozens of different bacteria in its scent pouch. That means each paste has a different recipe — and odor.
Our noses aren't sensitive enough to pick up their subtle differences. Still, Theis can sort them out by identifying the bacteria responsible. He does this by analyzing the recipe of each bacterium's DNA. Its building blocks appear in a very precise order  — or sequence. It is so precise and unique to the bacterium that this genetic sequence is a bit like a fingerprint.

Each spotted hyena seems to have its own mix of bacteria — and unique scent. A deep sniff of a pasted grass stalk can tell another hyena who marked it. And if it was a female, her scent also will signal whether she is pregnant or is nursing a cub.

Theis found that bacteria living in the scent pouch of hyenas produce the chemicals that give the animals their particular smell. Here’s why: Inside a hyena's scent pouch, bacteria feed on nutrients. These probably include fats and proteins derived from what the animal ate. Just like people, those microbes don't use everything they eat. Whatever doesn’t fuel a bacterium’s growth or reproduction will be expelled as waste. Some of those wastes are fatty materials that easily evaporate. They also make the paste stinky.

Theis has watched hyenas sniff the paste left by others. The animals then behave in one way or another, depending on what they learned.
"Females spent much more time sniffing pastes from other females," he says. This would “suggest that the scent of an alien female is very important.” And that makes sense, since females rule hyena clans. In contrast, the whiff of some alien male might not matter to her so much.d other samples from a hyena that has been temporarily drugged to sleep. Theis wants to know how hyenas rely on bacteria to make the distinctive scents that these animals use to identify one another.

Hyenas rely on these unique scents to identify one another by species, sex and clan. That is important information. “A critical part of most animals' behavior is an effective communication system,” Theis observes.

Each spotted hyena has a different ratio of dozens of different bacteria in its scent pouch. That means each paste has a different recipe — and odor.

Bacteria as “caller ID”

Animals are chock full of bacteria. In each of us, there are an estimated 10 single-celled microbes for every one of our own human cells. We’re outnumbered. But that's a good thing.
People and other animals share a symbiotic relationship with many bacteria. We have evolved to help each other. We give bacteria a place to live and food to eat. In turn, the bacteria work hard on our behalf. Bacteria on our skin, for example, form a protective coating. It fights off the germs that can make us sick. Bacteria in the gut help digest food, releasing the energy and nutrients we need. These good bacteria also crowd out many bad bugs that can trigger disease.
Those things have been studied for decades. Far newer: the role microbes play in behavior.

Theis and his colleagues reported their findings Dec. 3, 2013, in the Proceedings of the National Academy of Sciences.
Science News fos students

1. Vocabulary: to tuck; to rub; pungent; musky; odor; chock.
2. What is hyena-butter?
3. What is scent marking?
4. What produce the chemicals responsible for the smell of hyena butter?
5. Why does each hyena have a different scent?
6. What do hyenas use their “butter” for?
7. How many bacteria do we (humans) have in our bodies?
8. Why do we have a symbiotic relationship with bacteria?
9. How do bacteria help us?

Extra.Unit 5. Relations in the biocenosis

Bacteria as cloaking aid

Symbiotic bacteria aren’t just found in land species. The Hawaiian bobtail squid hosts glowing bacteria in its ink sac. The squid is tiny — just 30 millimetres (1.2 inches) long, not counting its tentacles. It hunts in shallow coastal waters. And bacteria give this animal an advantage: camouflage.
"It's like a Klingon cloaking device," says biologist Margaret McFall-Ngai. She and her research partner, microbiologist Edward Ruby, have studied the roles played by this microbe and its squid host for 25 years. Both scientists work at the University of Wisconsin in Madison.
The bacteria, called Vibrio fischeri (VIH-bree-oh FISH-er-eye), live inside a special light organ in the squid’s ink sac. The microbes glow with the same intensity and color as moon and starlight. That glow masks the presence of the squid as it hunts by night. Without this camouflage, the tiny squid could end up a midnight snack for many fish. But thanks to the microbes, a predator gazing toward the water's surface, where the squid feeds on small shrimp and worms, would see only what appears to be the lights of the moon and the stars, McFall-Ngai explains.

It's little wonder, then, that newborn squid actively collect V. fischeri within seconds of hatching. The bacteria are found in the same areas as these squid. Squid scoop up the microbes with the help of two finger-like protrusions. They’re known as appendages. These appendages — don’t confuse them with tentacles — are located on their light organ, tucked inside the front of the squid’s body cavity.
Thousands of tiny, moving, hairlike features — cilia — cover those protrusions.
The squid makes a circle with its appendages. Their cilia sweep through the sea water with a waving motion. This directs V. fischeri toward three pores on the surface of a squid’s light organ.
Once the bacteria are inside, the squid can control the bacteria's glow. In fact, the squid can even switch off their light. That way, the squid can mimic when a cloud blocks the light of the moon or stars.
The animal does this in two ways. One is by squeezing muscles in the ink sac to cover some of the glowing bacteria. The other is by controlling the amount of oxygen supplied to the microbes. The chemical reaction that makes the bacteria glow requires oxygen. The squid can constrict blood vessels leading to the light organ. That in turn reduces the availability of oxygen.
"These bacteria are small, but they are absolutely essential for proper behavioral function," says McFall-Ngai. Using them for camouflage is a very clever adaptation to life near the sea surface, she points out, "where there is nowhere to hide."
Science News for students

1. What is a symbiotic relationship?
2. Do you know a land species in which we can find symbiotic bacteria?
3. What is the benefit for the bacteria Vibrio fisherie?
4. What is the benefit for the Hawaiian bobtail squid?
5. Use a drawing to explain how the squid hunts and camouflages thanks to the bacteria.
6. Where in the squid do bacteria live?
7. How does the squid collect the bacteria?
8. Explain how the squid controls the bacteria’s glow.

Regeneration. Due on 8th May

Read the text in this website, watch the video about regeneration in planaria and answer these questions:

1. Why do humans prefer to avoid getting our limbs cut off?
2. Define regeneration.
3. What is a stem cell?
4. Why is important for scientists to learn about stem cells in other organisms?
5. What kind of “regenerative talents” do human have?
6. What is the difference between unidirectional and bidirectional regeneration?
7. Name the animals that demonstrate unidirectional regeneration and the animals with bidirectional regeneration.
   
   

   

Assesssment criteria: Unit 9

1. To place the position of an object in a system of reference made of two axes: X and Y.
2. To define and to label in a drawing: trajectory, distance covered and displacement.
3. To know the formula of the average speed and the unit used to measure it in the SI.
4. To solve problems in which two magnitudes are given (speed, distance or time) and the third one has to be worked out.
5. To change units of speed, distance and time.
6. To explain when a body in motion has acceleration and to know the formula of the average acceleration.
7. Given a movement, to classify it according to its trajectory(curvilinear or rectilinear) and to its speed (uniform or accelerated).