The Open Door Web Site
Facts and Figures Index
FREQUENTLY ASKED QUESTIONS
All of the questions listed below were originally sent to the SchoolsOnLine
Question: What is the average life span of a sugar maple? Is there any way to estimate its age by its height? Are sugar maples hardwood or softwood trees?
Answer: The sugar maple, Acer saccharum, is an important source of maple syrup and is grown particularly in the north eastern United States. In response to your first question, the true average life span of any tree species is difficult to determine. The number of individual trees dying at the difficult sapling stage, for example, may be high, and if the figures for these losses were to be included the average life span may seem unreasonably low. The final age of any individual tree will depend on a number of very variable factors such as soil depth, rainfall, competition, disease and human activity.
200 year-old sugar maples are known and I am sure that there are older individuals.
It is also quite difficult to estimate the age of a sugar maple by its height since the rate of growth will depend on a number of environmental factors. Once maximum height, which is usually about 30 metres but may be as much as 37.8 metres, is achieved it will remain unchanged and the tree will only increase in diameter as it gets older.
For further details on the two above questions I suggest you contact forestry organisations or those representing the maple syrup industry.
I can tell you quite definitely that the sugar maple is a hardwood tree, in fact the wood from a sugar maple is very dense, hard-grained and light coloured.
Question: Certain birds of prey swallow their food whole. The gizzard compresses some parts into a hard pellet. Which body parts do you think these pellets contain?
Answer: The pellets of which you write are formed from compressed indigestible materials, those which cannot be digested and used in metabolism by the birds of prey. The pellets usually consist of bones, feathers, fur or hair and possibly fish scales. The fragments found in the pellets of different birds can tell us much about the feeding habits of the birds in question.
Question: Do penguins have jointed legs? If they do why do they walk around with stiff legs?
Answer: I contacted a zoo where they have a collection of penguins to confirm my thoughts on this question. The simple answer is yes, penguins do have jointed legs. Although you may not be able to see them, perhaps because of the folds of abdominal skin that penguins often have, they do have ‘knee’ joints.
The way in which penguins walk is related to a number of factors. Their legs are relatively short and they are set far back on their bodies. This is why penguins, unlike most birds, have such an upright posture. Taking small, seemingly stiff steps may aid balance. I would also imagine that taking small steps would be to the advantage of a bird which often lives in very slippery conditions. I certainly take very tentative steps on ice.
Penguins can travel long distances overland. Rookeries (nesting sites) of the adelie penguin, for example, may be 50 miles from the sea and the penguins have to travel for 24 hours between feeding and reaching the nesting sites. In addition to walking penguins may often slide or ‘toboggan’ over the ice, propelling themselves forwards using their feet and their flippers. As their name implies, the very agile rockhopper penguins, often jump from stone to stone with their feet together.
It is thought that the short legs of the penguin are also useful when the penguin is standing still. The feet and the tail act as a tripod to hold the penguin upright for long periods without making the bird very tired. Remember that having short legs also cuts down the amount of heat lost through them, a consideration very important when you think about the extremely cold conditions in which most penguins live.
It is in water where the penguins are most agile. Here their short legs with their flat, webbed feet are used as rudders. Because the legs are set well back they carry out this function effectively.
Question: In cold climates, where do turtles go in the winter?
Answer: Marine turtles, such as the green turtle, can migrate into warmer waters in cold conditions. It is known that these migrations can be incredible journeys of many hundreds of miles.
Other turtles have to cope with the changes in the climate by different means. Many turtles may be said to hibernate during cold or otherwise adverse conditions although this is not strictly correct because hibernation only really relates to homeothermic or ‘warm-blooded’ animals which lower their body temperature during periods of hibernation. Since turtles are reptiles and are poikilothermic or ‘cold-blooded’ animals they do not truly hibernate but may enter a state of torpor or inactivity when conditions are not favourable.
One example of a turtle which goes into a state of inactivity in certain climatic conditions is the box turtle which is found as far north as New England and as far south as Mexico. The box turtle buries itself about 6-10 inches deep in soft soil or mud and, with a decreased rate of metabolism, may stay underground long enough to avoid extremely cold temperatures. If the winter is mild then it may only stay inactive for a few months between December and March. This type of turtle may also go underground in a similar way during very hot, dry weather in order to conserve water. Other turtles may take shelter under mud or piles of vegetation to avoid adverse conditions.
Some types of turtle may survive relatively mild cold spells by staying under the surface of the water in ponds and ditches. The soft-shelled turtle can sit at the bottom of a pond and breathe air from the surface because of its long, flexible neck as long as the water remains unfrozen.
To find more information on this subject I advise you to look at some reference books relating specifically to turtles and other reptiles. You could also contact organisations concerned with the welfare and conservation of these creatures.
Question: What determines the path a tornado will take?
Answer: In its most familiar form, a tornado is a funnel-shaped, vaporous mass, with winds rotating around a vertical axis at high speeds, which reaches down from a thundercloud o a squall line.
Violent storms often break out in central and southern states of the USA in springtime, when waves of warm, moist air from the Gulf of Mexico moving north and north-west, clash with invasions of cooler dry air coming down from the north and west. The month of May has the highest frequency of tornadoes, although April twisters tend to be more severe and take more lives. There are some 100,000 thunderstorms a year in the USA but only 1% spawn tornadoes. Of these, only 2% cause 70% of the deaths.
A tornado takes its direction - usually from the south-west to the north-east- from the movement of the parent thunderstorm cloud. The funnel advances at forward speeds that average about 30 miles per hour, but may exceed 70 miles per hour. The tornado may bounce and skip, rising briefly from the ground and then touching down again, and it can sway from side to side, sometimes tilting forward and sometimes back. Whatever track it eventually takes, whether it be straight or sinuous, the tornado belongs to the parent thunderstorm cloud and basically has to follow.
Although some rare twisters wreak havoc for hours, their lifespan is usually less than 15 minutes on average. A typical tornado descends from a severe thunderstorm as a crisp white funnel cloud. When it reaches the ground, the twister is affected by friction, quickly turns grey and black due to sucked in dust and debris and soon develops ragged edges. In the end, a tornado in effect becomes clogged with air and debris and its base is slowed by its contact with the ground. Although it can still generate swirling winds, a weakening tornado can no longer suck up the air in its path and gradually lags behind its parent thunderstorm. The funnel stretches out into a sinuous, ropy shape and begins to collapse, eventually dissipating completely.
Question: What are blood transfusions? What actually happens?
Answer: Transfusion is the process of transferring blood from a donor into the body of a recipient. Usually the donor and recipient are different people although it is possible to take blood from one person and give it back to them later when they need it for example after an operation.
The term ‘blood transfusion’ does not always mean that a recipient is receiving whole blood but this may be given in cases of severe blood loss and is blood with all the constituents it contained when donated although some of the clotting factors may have become less active during storage.
In other cases the blood which is donated is tested then separated into its components which may be distributed to hospitals when requested. The components of blood which may be transfused are:
Usually whole blood is taken from a donor although it is possible to quickly remove the plasma from donated blood and return the rest of the blood to the donor. This process is called plasmapheresis.
During a donor session about 0.5 litres of blood is drawn from the arm into a plastic, sterile pack which contains a solution designed to stop the blood clotting. The whole process of donation usually takes about 45 minutes. Blood is insfused into a recipient through special sterile giving sets and usually enters the body via the veins of the hand or forearm. Gravity plays a role here but the rate of infusion can be carefully controlled.
If you wish to find out further information do contact the National Blood Service through your regional transfusion centre.
Question: Could you assist me in finding information on green pigments other than chlorophyll?
Answer: This is an interesting question. First we have to remember that there are many different chlorophylls. Most of the green plants with which we are familiar contain chlorophylls a and b. Brown algae and diatoms contain chlorophylls a and c, red algae contain chlorophylls a and d and chlorophylls a and e are found in yellow-green algae. The colours of the different chlorophylls are described below:
Bacteriochlorophylls are similar to the chlorophylls mentioned above but differ a little in chemical structure. Unfortunately they are described as blue pigments so not very useful here.
I haven’t found any references to other green plant pigments but I hope this information is of use to you.
Question: Why is limestone (sedimentary rock) found on the top of a mountain in Wyoming?
Answer: Limestone is a sedimentary rock and was originally deposited at the bottom of ancient seas and oceans millions of years ago. The fact that these same limestones and other sedimentary rocks can be found at the top of a mountain in Wyoming, and even high up in the Himalayas, is the result of something called plate tectonics.
It has been discovered that the whole of the Earth’s surface (on land and under the sea) is made up of interlocking blocks of the Earth’s crust which are called ‘plates’. These plates move around over the planet, either moving away from each other, rubbing against each other or colliding with each other. The earth’s crust under the sea is thin an known as ‘oceanic crust’. On land it is thick and known as ‘continental crust’. Where oceanic crust collides with continental crust, mountain ranges with many volcanoes are produced (such as the Andes) and where continental crust collides with continental crust massive mountains (such as the Himalayas and the Alps) are the result.
This mountain building is a very long process. The Himalayas began to be formed about 40 million years ago as the Indian ‘plate’ moved northwards and collided with the Asiatic ‘plate’. As India moved northwards, vast amounts of sedimentary rocks in the seas, (such as limestones and sandstones), were pushed and squeezed in front of it. As India collided with Asia these sedimentary rocks were thrust upwards as the Himalayas were formed - and they are still growing! That is why today we can find these rocks hundreds of miles from today’s seas and thousands of metres up at the top of the highest mountains.
This same type of process occurred in the United States, but much longer ago, lifting rocks such as limestone high above sea level. This is why you can find limestone at the top of a mountain in Wyoming.
If you want to know more about this very exciting subject, see if you can find books on ‘Plate Tectonics ‘ and ‘Continental Drift’ in your local library. Also, any modern geological text book will cover this subject. Good hunting.
Question: In which ways do wetlands play an important role for birds? What is done to preserve wetlands for birds in general?
Answer: Wetlands, which include areas such as marshes, fens, lowland wet grasslands, broads and estuaries, are extremely important for birds. These areas are usually nutrient rich, highly productive areas supporting large populations of many different species of plants and animals upon which birds may feed. The diversity of plant species, from low-growing grasses to trees, help to provide a wide variety of habitats making them important and relatively safe nesting and roosting sites for many birds.
Wetlands are under constant threat from man’s activities such as farming and other forms of industry. It is important for the birds, as well as for other types of wildlife, that these areas are protected as much as possible from further development. Farmers, other potential developers, governments and the public are being made more aware of the importance of wetlands to wildlife. Organisations such as environmental groups are becoming increasingly involved in debates arising from threats to wetlands.
It is also important that most of these sites are managed in order to stop, or at least slow down, their gradual, natural succession into dryer areas. Labour intensive activities such as the building and maintenance of sluices, ditches and dams, tree control, reed planting, earth moving and the control of grazing must occur if water levels are to be maintained in many wetland areas. Public access to such sites must also be controlled for example through the building of paths.
Question: Why do we yawn when someone else yawns?
Answer: Yawning is a partially involuntary action. This means it can happen without us really thinking about it but we can also make ourselves yawn in some circumstances.
Most of our breathing movements are controlled by the breathing centre, which is situated in the medulla at the base of the brain. This part of the brain controls the involuntary actions of the body which we don’t usually have to think about in order for them to happen, such as breathing and heartbeat.
The conscious or thinking part of the brain, the cortex, is connected to the medulla and it can send messages to the breathing centre by which it can consciously control the rate of breathing. You will know, for example, that you can choose to slow down or speed up your rate of breathing whenever you want.
When we are resting and breathing slowly our lungs sometimes do not get rid of enough carbon dioxide so this builds up in our blood. This build up of carbon dioxide is detected by receptors and the breathing centre sends a message to the muscles around our lungs to take an extra deep breath which blows out excess carbon dioxide and brings more oxygen into the lungs. This extra deep breath is the yawn. Often a yawn can take us by surprise and sometimes we hardly notice that we are yawning. On the other hand we can also make ourselves yawn just by thinking about yawning.
When someone else yawns it is often very difficult not to yawn in response. Basically what is happening is that a type of auto-suggestion is taking place. Just thinking about yawning can make us yawn. When we see someone else yawn the conscious part of the brain thinks about yawning and this makes it send a message to the breathing centre. The message from the cortex causes the breathing centre to trigger the yawn response. It is possible to override this response and stifle the yawn but it isn’t always easy to do so!
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