My Science School

Science fiction stories do come true all the time. Less than a hundred years ago, space travel was a fantasy invented by storytellers such as H G Wells and Jules Verne. When we consider the extraordinary advances made in the fields of travel and communications in the past century, it is tempting to believe that Star Trek may in the future be nearer to reality than at present seems possible!

Science fiction introduces us to elaborate, futuristic worlds that often sound like nothing more than a dream. But humanity has made incredible technological advancements over the past 100 years, and many of the ideas predicted in science fiction have now become reality.

Some predictions, like self-driving cars, are still in the early stages, but scientists and engineers have reached many other milestones first described in fiction, such as bringing people to the moon.

In 1865, author Jules Verne released From Earth to the Moon, which described three Americans' mission to launch a spacecraft and land on the moon. Parts of the novel were similar to the first real moon landing, which occurred 104 years later.

Both the NASA astronauts and Verne's characters launched from Florida. NASA's command module was named Columbia in another similarity to Verne's fictional spacecraft, the Columbia. NASA astronauts Neil Armstrong and Edwin "Buzz" Aldrin succeeded in walking on the lunar surface in 1969 while Michael Collins remained in the spacecraft. The three men in Verne's novel, however, never stepped foot on the moon.

NASA has acknowledged other similarities between Apollo 11 and Verne's novel as well. For example, the space agency said the Columbiad's shape and size closely resembled the Apollo spacecraft. The novel also claimed a telescope would be able to see the Columbiad mission's progress. When an explosion caused a malfunction during the Apollo 13 mission in 1970, a telescope at Johnson Space Center was able to see the accident, which took place more than 200,000 miles away (300,000 kilometres).

3D holograms have been featured in sci-fi for decades. In 2017, an Australian company claimed it has managed to produce a hologram table that resembles the futuristic holograms from the original "Star Wars" movie. Princess Leia called for Luke Skywalker's help using a holographic message in the 1977 "Star Wars" movie. Since then, scientists have worked on turning this technology into reality.

Euclideon, an Australian company, says it has made the first multi-user hologram table in the world. As many as four people can interact with the hologram at once using motion-tracking glasses. Though Euclideon's invention has been met with some scepticism, but New Atlas reported in November 2018 that the company is moving forward with bringing the hologram technology to market.

"Star Trek" featured replicators that could 3D print food and everyday objects in a few seconds. Scientists are now using 3D printing technology to make objects out of plastic, metal, and glass, though the process is not nearly as fast.

The New York-based nonprofit Mattershift says it has developed carbon nanotube membranes that could separate and put together individual molecules.

Forbes reported that Mattershift CEO Rob McGinnis says the membranes could help scientists make anything out of a set of basic molecular building blocks. "We're talking about printing matter from the air," McGinnis said, according to Forbes. "Imagine having one of these devices with you on Mars. You could print food, fuels, building materials, and medicines from the atmosphere and soil or recycled parts without having to transport them from Earth." In addition, startups like Natural Machines are working on making 3D food printers commercially available.

The Iron Man suit has become legendary since first appearing in Marvel Comics. People won't be flying around in suits anytime soon, but the US military is developing high-tech suits that will mirror some of Iron Man's capabilities. The military's TALOS program – short for Tactical Assault Light Operator Suit – aims to enhance human combat.

TALOS will take in huge amounts of data from drones, naval sensors, and reconnaissance aircraft to better inform soldiers, Military Times reported. The suit is expected to be light and include life support systems that will track soldiers' vitals. 3D sound pickups built into the suit will also help soldiers figure out where incoming fire and vehicles are coming from.

The biggest problems of space travel all have to do with the enormous distances that are involved. Using today’s technology, it would take years to reach even the nearest planets, and generations of space travellers would live and die on a journey to more distant ones. For this to happen, spacecraft will need to be self-supporting or able to travel faster than the speed of light.

The first hazard of a human mission to Mars is also the most difficult to visualize because, well, space radiation is invisible to the human eye. Radiation is not only stealthy, but considered one of the most menacing of hazards.

Above Earth’s natural protection, radiation exposure increases cancer risk, damages the central nervous system, can alter cognitive function, reduce motor function and prompt behavioral changes. To learn what can happen above low-Earth orbit, NASA studies how radiation affects biological samples using a ground-based research laboratory.

Mars is, on average, 140 million miles from Earth. Rather than a three-day lunar trip, astronauts would be leaving our planet for roughly three years. While International Space Station expeditions serve as a rough foundation for the expected impact on planning logistics for such a trip, the data isn’t always comparable. If a medical event or emergency happens on the station, the crew can return home within hours. Additionally, cargo vehicles continual resupply the crews with fresh food, medical equipment, and other resources. Once you burn your engines for Mars, there is no turning back and no resupply.

Planning and self-sufficiency are essential keys to a successful Martian mission. Facing a communication delay of up to 20 minutes one way and the possibility of equipment failures or a medical emergency, astronauts must be capable of confronting an array of situations without support from their fellow team on Earth.

The variance of gravity that astronauts will encounter is the hazard of a human mission. On Mars, astronauts would need to live and work in three-eighths of Earth’s gravitational pull for up to two years. Additionally, on the six-month trek between the planets, explorers will experience total weightlessness. 

Besides Mars and deep space there is a third gravity field that must be considered. When astronauts finally return home they will need to readapt many of the systems in their bodies to Earth’s gravity. Bones, muscles, cardiovascular system have all been impacted by years without standard gravity. To further complicate the problem, when astronauts transition from one gravity field to another, it’s usually quite an intense experience. Blasting off from the surface of a planet or a hurdling descent through an atmosphere is many times the force of gravity.

As there are billions of planets in our universe, it is likely that some of them could support life, but the vast distances that would have to be travelled to reach them are at present an immense problem. More possible is the idea that humans could build self-supporting communities on nearby planets. Ideally, these would need to be enclosed, containing their own atmosphere and able to support a variety of plant and animal life just as our planet does. Experiments are being made t9 see if it is possible to build artificial ecosystems like this here on Earth.

We know of only one living planet: our own. But we know it very well. As we move to the next stage in the search for alien life, the effort will require the expertise of planetary scientists, heliophysicists and astrophysicists. However, the knowledge and tools NASA has developed to study life on Earth will also be one of the greatest assets to the quest.

There are two main questions in the search for life: With so many places to look, how can we focus in on the places most likely to harbor life? What are the unmistakable signs of life -- even if it comes in a form we don't fully understand?

"Before we go looking for life, we're trying to figure out what kinds of planets could have a climate that's conducive to life," del Genio said. "We're using the same climate models that we use to project 21st century climate change on Earth to do simulations of specific exoplanets that have been discovered, and hypothetical ones."

Del Genio recognizes that life may well exist in forms and places so bizarre that it might be substantially different from Earth. But in this early phase of the search, "We have to go with the kind of life we know," he said.

Further, we should make sure we use the detailed knowledge of Earth. In particular, we should make sure of our discoveries on life in various environments on Earth, our knowledge of how our planet and its life have affected each other over Earth history, and our satellite observations of Earth’s climate.

Above all else, that means liquid water. Every cell we know of -- even bacteria around deep-sea vents that exist without sunlight -- requires water.

The saying that there is nothing new under the Sun is strangely true. The stuff that makes up everything on Earth —animals, plants, rocks, water — cannot be destroyed, although it can be changed from one form to another. Living things are almost entirely made up of six elements: carbon, oxygen, hydrogen, nitrogen, phosphorous and sulphur. When a plant or animal dies, it decomposes. Gradually, its body breaks down, and the elements it was made of go back into the soil or water. These elements in time are taken up by new plants, which in turn are eaten by animals. This cycle of elements being released and re-used can take millions of years, but it is quite likely that within your body there are chemicals that were once part of a prehistoric plant — or even a dinosaur!

Eventually, all living things die. And except in very rare cases, all of those dead things will rot. But that’s not the end of it. What rots will wind up becoming part of something else. This is how nature recycles. Just as death marks the end of an old life, the decay and decomposition that soon follow provide material for new life. “Decomposition breaks apart dead bodies,” explains Anne Pringle. She’s a biologist at Harvard University in Cambridge, Mass.

When any organism dies, fungi and bacteria get to work breaking it down. Put another way, they decompose things. (It’s the mirror image of composing, where something is created.) Some decomposers live in leaves or hang out in the guts of dead animals. These fungi and bacteria act like built-in destructors.

Soon, more decomposers will join them. Soil contains thousands of types of single-celled fungi and bacteria that take things apart. Mushrooms and other multi-celled fungi also can get into the act. So can insects, worms and other invertebrates. Yes, rotting can be yucky and disgusting. Still, it is vitally important. Decomposition aids farmers, preserves forest health and even helps make biofuels. That is why so many scientists are interested in decay, including how climate change and pollution may affect it.

Decomposition isn’t just the end of everything. It’s also the start. Without decay, none of us would exist. “Life would end without rot,” observes Knute Nadelhoffer. He’s an ecologist at the University of Michigan in Ann Arbor. “Decomposition releases the chemicals that are critical for life.” Decomposers mine them from the dead so that these recycled materials can feed the living.

The most important thing recycled by rot is the element carbon. This chemical element is the physical basis of all life on Earth. After death, decomposition releases carbon into the air, soil and water. Living things capture this liberated carbon to build new life. It’s all part of what scientists call the carbon cycle. The carbon cycle starts with plants. In the presence of sunlight, green plants combine carbon dioxide from the air with water. This process, called photosynthesis, creates the simple sugar glucose. It’s made of nothing more than the carbon, oxygen and hydrogen in those starting materials.

Wind, moving water and sunshine are always to be found somewhere on the Earth. All of these can be harnessed to provide energy. Wind farms, consisting of fields of enormous windmills, have been set up in many parts of the world to capture the wind's energy. Hydroelectric power uses the force of water hurtling over dams. Solar panels are warmed by the Sun and can be used to heat water and homes. At the moment, these methods are not able to produce all the energy that the world needs, but they hold out hope for the future.

A renewable resource is one that can be used repeatedly and does not run out because it is naturally replaced. A renewable resource, essentially, has an endless supply such as solar energy, wind energy, and geothermal pressure. Other resources are considered renewable even though some time or effort must go into their renewal (e.g., wood, oxygen, leather, and fish). Most precious metals are renewable also. Although precious metals are not naturally replaced, they can be recycled because they are not destroyed during their extraction and use.

A renewable resource is different from a nonrenewable resource; a nonrenewable resource is depleted and cannot be recovered once it is used. As the human population continues to grow and demand for renewable resources increases. Types of biofuel include biodiesel, an alternative to oil, and green diesel, which is made from algae and other plants. Other renewable resources include oxygen and solar energy. Wind and water are also used to create renewable energy. For example, windmills harness the wind's natural power and turn it into energy.

The United States currently relies heavily on coal, oil, and natural gas for its energy. Fossil fuels are non-renewable, that is, they draw on finite resources that will eventually dwindle, becoming too expensive or too environmentally damaging to retrieve. In contrast, the many types of renewable energy resources-such as wind and solar energy-are constantly replenished and will never run out.

Most renewable energy comes either directly or indirectly from the sun. Sunlight, or solar energy, can be used directly for heating and lighting homes and other buildings, for generating electricity, and for hot water heating, solar cooling, and a variety of commercial and industrial uses.

The sun’s heat also drives the winds, whose energy, is captured with wind turbines. Then, the winds and the sun’s heat cause water to evaporate. When this water vapor turns into rain or snow and flows downhill into rivers or streams, its energy can be captured using hydroelectric power.

Living things can grow and reproduce themselves. Given the right conditions, they can continue to do this for millions of years. But some of the Earth’s resources cannot renew themselves. When they have been used up, there will be no more. Perhaps the most important of these non-renewable resources are what are known as fossil fuels. Both oil and coal were made millions of years ago when the bodies of prehistoric plants and animals were crushed under enormous pressure beneath moving rock. There is a limited supply of these fuels, making it necessary for us to develop energy sources that cannot run out.

Renewable and nonrenewable resources are energy sources that human society uses to function on a daily basis. The difference between these two types of resources is that renewable resources can naturally replenish themselves while nonrenewable resources cannot. This means that nonrenewable resources are limited in supply and cannot be used sustainably.

There are four major types of nonrenewable resources: oil, natural gas, coal, and nuclear energy. Oil, natural gas, and coal are collectively called fossil fuels. Fossil fuels were formed within the Earth from dead plants and animals over millions of years—hence the name “fossil” fuels. They are found in underground layers of rock and sediment. Pressure and heat worked together to transform the plant and animal remains into crude oil (also known as petroleum), coal, and natural gas.  

The plants and animals that became fossil fuels lived in a time called Carboniferous Period, around 300 to 360 million years ago. The energy in the plant and animal remains originally came from the sun; through the process of photosynthesis, solar energy is stored in plant tissues, which animals then consume, adding the energy to their own bodies. When fossil fuels are burned, this trapped energy is released.

Crude oil is a liquid fuel fossil fuel that is used mostly to produce gasoline and diesel fuel for vehicles, and for the manufacturing of plastics. It is found in rocks below Earth’s surface and is pumped out through wells. 

Natural gas is widely used for cooking and for heating homes. It consists mostly of methane and is found near oil deposits below Earth’s surface. Natural gas can be pumped out through the same wells used for extracting crude oil.  Coal is a solid fossil fuel that is used for heating homes and generating power plants. It is found in fossilized swamps that have been buried beneath layers of sediment. Since coal is solid, it cannot be extracted in the same manner as crude oil or natural gas; it must be dug up from the ground. Nuclear energy comes from radioactive elements, mainly uranium, which is extracted from mined ore and then refined into fuel. 

Unfortunately, human society is—for the time being—dependent on nonrenewable resources as its primary source of energy. Approximately 80 percent of the total amount of energy used globally each year comes from fossil fuels. We depend on fossil fuels because they are energy-rich and relatively cheap to process. But a major problem with fossil fuels, aside from their being in limited supply, is that burning them releases carbon dioxide into the atmosphere. Rising levels of heat-trapping carbon dioxide in the atmosphere is the main cause of global warming. 

Alternative energy sources, such as wind and solar energy, are a possible solution to the depletion of nonrenewable sources. Both of these clean energy sources are available in unlimited supply.

Life on Earth cannot go on forever because it depends on the Sun and, like all stars, our Sun will eventually die. However, that will happen billions of years in the future. In the meantime, we need to be concerned about the way in which we are using our planet now, so that it will continue to provide a home for all the living things that share it with us in the next century and beyond.

The biological and geological future of Earth can be extrapolated based upon the estimated effects of several long-term influences. These include the chemistry at Earth's surface, the rate of cooling of the plant’s interior, the gravitational interactions with other objects in the Solar System, and a steady increase in the Sun’s luminosity. An uncertain factor in this extrapolation is the ongoing influence of technology introduced by humans, such as climate engineering, which could cause significant changes to the planet. The current Holocene extinction is being caused by technology and the effects may last for up to five million years. In turn, technology may result in the extinction of humanity, leaving the planet to gradually return to a slower evolutionary pace resulting solely from long-term natural processes.

The luminosity of the Sun will steadily increase, resulting in a rise in the solar radiation reaching the Earth. This will result in a higher rate of weathering of silicate minerals, which will cause a decrease in the level of carbon dioxide in the atmosphere. In about 600 million years from now, the level of carbon dioxide will fall below the level needed to sustain C3 carbon fixation photosynthesis used by trees. Some plants use the C4 carbon fixation method, allowing them to persist at carbon dioxide concentrations as low as 10 parts per million. However, the long-term trend is for plant fe to die off altogether. The extinction of plants will be the demise of almost all animal life, since plants are the base of the food chain on Earth.

In about one billion years, the solar luminosity will be 10% higher than at present. This will cause the atmosphere to become a "moist greenhouse", resulting in a runaway evaporation of the oceans. As a likely consequence, plate tectonics will come to an end and with them the entire carbon cycle. Following this event, in about 2–3 billion years, the planet's magnetic dynamo may cease, causing the magnetosphere to decay and leading to an accelerated loss of volatiles from the outer atmosphere. Four billion years from now, the increase in the Earth's surface temperature will cause a runaway greenhouse effect, heating the surface enough to melt it. By that point, all life on the Earth will be extinct. The most probable fate of the planet is absorption by the Sun in about 7.5 billion years, after the star has entered the red giant phase and expanded beyond the planet's current orbit.

In many parts of the world, life expectancy — the number of years that a person can expect to live — is increasing. A thousand years ago, 40 might have seemed a good age for an adult to reach. Now we expect to live twice as long. Of course, these are just averages. Since records began there have been exceptional people who lived to 80 and beyond, but for most people, the dangers of dying of disease, accident, war or starvation were very high. Childhood in particular was a dangerous time. A woman might give birth to more than 10 children, none of them living to adult-hood. We must not forget that there are parts of the world where this is still true, and billions of people still die each year from lack of food or medical care.

Demographic research suggests that at the beginning of the 19th century no country in the world had a life expectancy longer than 40 years. Every country is shown in red. Almost everyone in the world lived in extreme poverty, we had very little medical knowledge, and in all countries our ancestors had to prepare for an early death.

Over the next 150 years some parts of the world achieved substantial health improvements. A global divide opened. In 1950 the life expectancy for newborns was already over 60 years in Europe, North America, Oceania, Japan and parts of South America. But elsewhere a newborn could only expect to live around 30 years. The global inequality in health was enormous in 1950: People in Norway had a life expectancy of 72 years, whilst in Mali this was 26 years. Africa as a whole had an average life expectancy of only 36 years, while people in other world regions could expect to live more than twice as long.

The decline of child mortality was important for the increase of life expectancy, but as we explain in our entry on life expectancy increasing life expectancy was certainly not only about falling child mortality – life expectancy increased at all ages.

Such improvement in life expectancy — despite being exclusive to particular countries — was a landmark sign of progress. It was the first time in human history that we achieved sustained improvements in health for entire populations. After millennia of stagnation in terrible health conditions the seal was finally broken.

Now, let’s look at the change since 1950. Many of us have not updated our world view. We still tend to think of the world as divided as it was in 1950. But in health — and many other aspects — the world has made rapid progress. Today most people in the world can expect to live as long as those in the very richest countries in 1950. The United Nations estimate a global average life expectancy of 72.6 years for 2019 – the global average today is higher than in any country back in 1950. According to the UN estimates the country with the best health in 1950 was Norway with a life expectancy of 72.3 years.

The three maps summarize the global history of life expectancy over the last two centuries: Back in 1800 a newborn baby could only expect a short life, no matter where in the world it was born. In 1950 newborns had the chance of a longer life if they were lucky enough to be born in the right place. In recent decades all regions of the world made very substantial progress, and it were those regions that were worst-off in 1950 that achieved the biggest progress since then. The divided world of 1950 has been narrowing.

Globally the life expectancy increased from less than 30 years to over 72 years; after two centuries of progress we can expect to live much more than twice as long as our ancestors. And this progress was not achieved in a few places. In every world region people today can expect to live more than twice as long.

The global inequalities in health that we see today also show that we can do much better. The almost unbelievable progress the entire world has achieved over the last two centuries should be encouragement enough for us to realize what is possible.

Human beings are mammals, which mean that their young develop inside the mother until they are ready to be born. This development takes place inside the womb or uterus, where the baby gains the nutrients and oxygen it needs for growth from its mother’s own blood, supplied through the umbilical cord.

A woman’s ovaries usually release one egg each month. As it travels through the fallopian tube towards the uterus, it may be fertilized by a sperm that has enter her bady during sexual intercourse.

As soon as it is fertilized, the egg call begins to divide, until it becomes a ball of cells called a blastocyst. This ball then implants itself in the wall of the uterus.

After four weeks, the blastocyst has become an embryo. Its brain, spin and limbs are already forming and its heart will soon begin to beat.

At 12 week, the embryo is now called a foetus. All its organs are formed. For the rest of the time before it is born, it simply has to grow.

From 38 weeks onwards, the baby is ready to be born. It moves down into the pelvis. At birth, the cervix gradually opens and the baby is born through the vagina.

The characteristics of individual human beings are passed from one generation to the next in their chromosomes. Each of our parents gives us 23 chromosomes, making 46 in all. That means that we have two versions of each of our genes, but one is often dominant. We see the effect of the dominant gene, but the other (recessive) gene is still there and can be passed to our children.

The Law of Inheritance – Mendel’s Law, is significant in comprehending how characteristics or traits are genetically passed from one generation to the next. Heredity is the process through which a new individual acquires traits from its parents during the event of reproduction.

Every individual has 23 pairs of chromosomes, each of which comes from the father and the mother. As genes are present on chromosomes, we receive two copies of each gene from paternal and maternal side respectively and one pair of sex chromosomes from each parent to form 46 chromosomes on the whole.

Traits acquired through inheritance are determined by rules of heredity. These traits are coded in our DNA and hence can be passed to the offspring (eye color, hair color, height etc.). Thus for each trait, there are two versions in a child. During the cell division process, genetic information (DNA structure) containing chromosomes are transferred into the cell of the new individual, therefore, passing traits to the next generation.

Gestation is the length of time between conception — the fertilization of an egg by a sperm — and the birth of the baby that grows from the fertilized egg. The length of gestation varies according to the species.

Gestation, in mammals, the time between conception and birth, during which the embryo or fetus is developing in the uterus. This definition raises occasional difficulties because in some species (e.g., monkeys and man) the exact time of conception may not be known. In these cases the beginning of gestation is usually dated from some well-defined point in the reproductive cycle (e.g., the beginning of the previous menstrual period).

The length of gestation varies from species to species. The shortest known gestation is that of the Virginian opossum, about 12 days, and the longest that of the Indian elephant, about 22 months. In the course of evolution the duration of gestation has become adapted to the needs of the species. The degree of ultimate growth is a factor, smaller animals usually having shorter periods of gestation than larger ones. Exceptions are the guinea pig and related South American rodents, in which gestation is prolonged (averaging 68 days for the guinea pig and 111 days for the chinchilla). The young of these species are born in a state of greater maturity than are those of the rat with its period of 22 days. Another factor is that, in many species with restricted breeding seasons, gestation is adjusted so that birth coincides with the period when food is most abundant. Thus the horse, a spring breeder with 11 months’ gestation, has its young the following spring, as does the sheep, a fall breeder with a five months’ gestation. Animals that live in the open tend to have longer gestations and to bear young that have reached a state of greater maturity than do animals that can conceal their young in underground burrows or in caves. Marsupials generally have short gestations—e.g., 40 days for the largest kangaroos. The young, born in an extremely immature state, transfer to the pouch in which gestation may be said to continue.

Embryos of some species experience an arrest in development that greatly prolongs gestation. This is especially true of the fur-bearing carnivores the martens and weasels. Embryos of the European badger and American marten, which breed in July and August, develop for a few days, and then lie dormant in the uterus, being implanted in January. Birth occurs in March. Of the total gestation period of 250 days, growth occurs during only 50. Delayed implantation also occurs in mice and other small rodents that become pregnant while they are still suckling a litter.

Either a single factor or a great number of minor factors, all culminating at or near one date, determine the length of gestation. Several minor variations are known: in man, gestation for males is three to four days longer than that for females; and in cattle, bulls are carried about one day longer than heifers. In both species gestation of twins is five to six days less than for singlet’s. In animals such as the rabbit or pig, which bear many young at a time, gestation is shorter for larger litters than for smaller ones. Heredity also influences gestation; in cattle the mean gestation period for Holstein-Friesians is 279 days; for Brown Swiss, 290 days; other breeds fall between these extremes. When hybrids are produced by crossing two species with different gestation periods, the hybrid is carried for a period lying somewhere between those of the two parents and tending toward the mother’s species. Thus a mare carries a mule foal (fathered by a jackass) about 10 days longer than the normal period for the horse (about 337 days). For human gestation, see pregnancy.

Human beings are far from being the longest-living animals. The giant tortoise can reach 150 years, while several aquatic creatures, such as the killer whale and some species of sea anemone, can survive for well over 80 years. At the other end of the scale, the adult mayfly lives for less than two days. The plant kingdom has far longer-living species. Several trees, such as the yew and giant sequoia, live for thousands of years.

There are tortoises alive today that were 25 to 50 years old when Charles Darwin was born. There are whales swimming the oceans with 200-year-old ivory spear points embedded in their flesh. There are cold-water sponges that were filter-feeding during the days of the Roman Empire. In fact, there are a number of creatures with life spans that make the oldest living human seem like a spring chicken in comparison.

Greenland shark: This shark lives in Arctic waters and slowly grows to an average length of 16 feet. It scavenges for its food and is attracted to the smell of rotting meat in the ocean. It's also known to primarily live in deeper ocean depths compared to other sharks. A group of scientists conducted radiocarbon testing on the eye lens of 28 female sharks and determined its life span to reach at least 272 years. They concluded that the Greenland shark is the longest-living vertebrae known to man.

Geoducks: These large saltwater clams that are native to the Puget Sound and have been known to live for at least 160 years. They are characterized by their long 'necks', or siphons, which can grow to more than 1 meter long.

Tuatara: The word "dinosaur" is commonly used to describe an old person, but when it refers to tuataras, the term is perfectly metaphorical. The two species of tuatara alive today are the only surviving members of an order that flourished about 200 million years ago — they are living fossils. They are also among the longest-lived vertebrates on Earth, with some individuals living for between 100 and 200 years.

Lamellibrachia tube worms: These colorful deep sea creatures are tube worms (L. luymesi) that live along hydrocarbon vents on the ocean floor. They have been known to live 170 years, but many scientists believe there may be some that have lived for more than 250 years.

Red sea urchins: The red sea urchin or Strongylocentrotus franciscanus is found only in the Pacific Ocean, primarily along the West Coast of North America. It lives in shallow, sometimes rocky, waters from the low-tide line down to 90 meters, but they stay out of extremely wavy areas. They crawl along the ocean floor, using their spines as stilts. If you discover one, remember to respect your elders — some specimens are more than 200 years old.

Bowhead whales: Also known as the Arctic whale, the bowhead is by far the longest living mammal on Earth. Some bowhead whales have been found with the tips of ivory spears still lodged in their flesh from failed attempts by whalers 200 years ago. The oldest known bowhead whale was at least 211 years old.

Koi: Koi are an ornamental, domesticated variety of the common carp. They are common in artificial rock pools and decorative ponds. Amazingly, some varieties are capable of living more than 200 years. The oldest known koi was Hanako, a fish that died at the age of 226 on July 7, 1977.

Tortoises: Tortoises are considered the longest living vertebrates on Earth. One of their oldest known representatives was Harriet, a Galápagos tortoise that died of heart failure at the age of 175 years in June 2006 at a zoo owned by the late Steve Irwin. Harriet was considered the last living representative of Darwin's epic voyage on the HMS Beagle. An Aldabra giant tortoise named Adwaita died at the rumored age of 250 in March 2006.

Two things affect the way in which living things grow and age. The first is their genetic make-up — the genes that they have inherited from their parents. The DNA in their chromosomes controls the way that cells divide to cause the growth of the young organism, its coming to maturity and its aging. The other important factor is the environment and conditions that the organism experiences — how much of the right kind of food it eats, where it lives, the climate and the kinds of events and accidents that happen to it.

Every living organism begins life as a single cell. Unicellular organisms may stay as one cell but they grow too. Multicellular organisms add more and more cells to form more tissues and organs as they grow.

The Growth and development of living organisms are not the same things. Growth is the increase in size and mass of that organism. Development involves the transformation of the organism as it goes through the growth process.

Think of a newly born baby. It has all the features of a fully-grown adult, but they are very tiny. As the years go by, they become big and become a young person like you, and later on, into a fully grown adult, maintaining all the features that they are born with. This is growth. But in their mummy’s tummy, they started off as a single cell and transformed into a zygote and into a foetus before transforming into a tiny baby.

In some organisms, growing involves drastic transformation. Think of a butterfly for instance. It starts off as a cell (egg). Then it transforms into a caterpillar, then into a pupa (chrysalis), and then pops out as a beautiful butterfly.

Plants often start from a tiny seed, and grow into a big tree. One thing common to all organisms is that they grow or develop to look just like their parent species, even though there may be some slight variations resulting from the mixing of cells by the parents. 

Cell growth and development include its repair. As cells grow old, they wear off. Sometimes they suffer injury and bruises, but they are able to repair themselves by growing new cells in a process called Mitosis.

As living things grow, they undergo a process called aging (age). As they get close to the end of their lifespan, their ability to carry out life functions reduces. Eventually, they die to end the process of life.

DNA is an abbreviation of the name of a chemical: deoxyribonucleic acid. It is DNA that contains the instructions for making and controlling every living thing. Inside the nucleus of a cell, the DNA forms chromosomes. Living things have different numbers of chromosomes. Human beings have 46, arranged in 23 pairs. Each of us has inherited one half of each chromosome pair from our father and the other half from our mother. A gene is a small part of the DNA molecule that can make one of the proteins that the living organism needs.

Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA). Mitochondrial are structures within cells that convert the energy from food into a form that cells can use.

The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.

DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.

An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell.

Living things are said to be animate. Inanimate things are not living. Metal, plastic and glass, for example, are inanimate. All animate things are able to do six things that inanimate things cannot.

Although seemingly diverse, living things, or organisms, share certain essential characteristics. The most recent classification system agreed upon by the scientific community places all living things into six kingdoms of life, ranging from the simplest bacteria to modern-day human beings. With recent innovations such as the electron microscope, scientists peered inside cells and began to understand the intracellular processes that defined life.

Composition

Cells compose all life, performing the functions necessary for an organism to survive in its environment; even the most primitive of life forms, bacteria, consists of a single cell. While peering through a microscope at slices of cork tissue in the late 17th century, scientist Robert Hooke discovered numerous tiny compartments which he coined “cells.” After several developments regarding cell structure and function, Robert Virchow compiled a book, “Cellular Pathology,” describing the nature of cells in relation to life. He formed three conclusions: cells form the basis of all life, cells beget other cells and cells can exist independent of other cells.

Energy Use

All processes occurring within organisms, whether single-celled or multicellular, expend energy. The method of procuring that energy, however, differs between organisms. Organisms called autotrophs make their own energy while heterotrophs must feed to obtain their energy needs. Autotrophs such as plants and some bacteria produce their own food by converting carbon dioxide and water into sugar with the aid of the sun’s energy via photosynthesis. Other autotrophic bacteria use chemicals such as sulfur to make energy in a process called chemosynthesis. The energy organisms need comes in the form of a molecule called ATP, or adenosine triphosphate. Living things make ATP by breaking down glucose.

Response

Organisms use their senses to obtain information from and have the capability of reacting to stimuli in their environments. Even unicellular organisms such as bacteria and seemingly immobile plants can respond to stimuli. Plants such as sunflowers can sense heat and light, so they turn toward the sun’s rays. Predators such as cats can track their prey with keen senses of vision, smell and hearing and then hunt them down with superior agility, speed and strength.

Growth

Living things grow and change through the process of cell division, or mitosis. In organisms composed of more than one cell, mitosis either repairs damaged cells or replace older ones that have died. Additionally, multicellular organisms grow larger in size by increasing the number of cells in their bodies. Unicellular organisms take in nutrients and enlarge. They grow to a certain point and then must divide into two new daughter cells. The process of mitosis takes place in four phases. Certain signals trigger cells to divide. The cell replicates its genetic information, resulting in two exact copies of the gene-bearing structures called chromosomes. Cellular structures separate the chromosome copies, moving them to different sides of the cell. The cell then pinches itself down the middle, creating a new barrier to separate the two new cells.

Reproduction

For a species or organism to continue existing, members of the species must reproduce, either asexually or sexually. Asexual reproduction produces offspring that exactly resemble the parent organism. Certain members in each of the kingdoms of life can reproduce asexually. Bacteria from Kingdoms Archaebacteria and Eubacteria, amoeba of the Kingdom Protista and yeast of Kingdom Fungi use binary fission to simply divide in two, resulting in two identical daughter cells. Worms called planaria can break off a segment that grows into a new organism. Plants such as potatoes form buds which, when cut off and planted, will produce a new potato plant. Sexual reproduction, which allows a mixing of genes from two individuals of a species, evolved from asexual reproduction because the benefits of sex outweigh its costs.

Adaptation

Since the beginning of life, organisms have adapted and evolved to survive according to their environments. Those individuals unable to adapt to changing conditions will die or be unable to pass on much of their genes to the next generation. Many times in the history of the earth, entire species, including many dinosaur groups, have died out when they failed to respond appropriately to environmental changes such as droughts or cooling climates. The environment selects for those individuals best acclimated to live under specific conditions; these creatures have the best selections of mates and will contribute to a greater percentage of descendants.