Life on earth

Question 1

What is Classification?

Answer 1

Similarities and differences between living things on Earth are used to put them into groups. This process is called classification. the first big division of living things in the classification system is called the five kingdoms

Question 2

what is Species?

Answer 2

A species is a group of organisms that can breed together to produce fertile offspring.

Question 3

A horse and donkey are different species - how do we know that?

Answer 3

The most common example to show this is with horses and donkeys. A horse and donkey can breed together: the offspring is called a mule. The mule is infertile, which shows that the horse and donkey are a different species.

Question 4

what is Adaptation?

Answer 4

Adaptation

Adaptations are features that help an organism survive in the environment it lives in.

Question 5

What do adaptations increase?

Answer 5

adaptations increase the organism’s chance of surviving. If the chances of survival are increased it also increases the chances that the organism will successfully reproduce.

Question 6

What is a food web ?

Answer 6

A food web is simply a number of food chains joined together. It shows how the loss of one organism has an effect of other organisms in the food web. This is called the interdependence of living things

Question 7

Give 4 common factors that can cause a species to become extinct?

Answer 7

Here are some factors that can cause a species to become extinct:
rapid changes to the environment, such as the climate
new diseases
new predators
new competitors.

Question 8

why are we very successful predators?

Answer 8

We compete with other living things for space, food and water, and are very successful predators

Question 9

How do we know that many species have become extinct?

Answer 9

Fossils

Question 10

what is a quagga?

Answer 10

The quagga has a horse/zebra like face and stripes similar to a zebra.The last quagga alive in the wild was shot in the late 1870s. Some animals - such as the quagga - are extinct because of the direct activity of humans.

Question 11

What is The dodo?

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Answer 11

The dodo was a large flightless bird that lived on Mauritius, one of a group of islands in the Indian Ocean. The Dodo is extinct because of the indirect activity of humans.

Question 12

why did the dodo become extinct?

Answer 12

The Mauritius islands were uninhabited, and the dodo had no natural predators. Then Mauritius were colonised by the Dutch in 1638. Dodos were hunted for food and easy to catch, because they were not afraid of people.

Question 13

which new competitors did the Dutch bring to the Mauritus in the 17th century?

Answer 13

The Dutch also brought new competitors to the islands, such as pigs, cats and rats, which ate the dodos’ eggs and young and were finally responsible for the extinction of the dodo.

Question 14

What do plants do with energy from the sun?

Answer 14

Plants harness light energy to drive food production. By the process of photosynthesis,

Question 15

Nearly all organisms are dependent on energy from the what ?

Answer 15

The Sun - Nearly all organisms are dependent on energy from the Sun

Question 16

Describe the process of photosynthesis,

Answer 16

organic compounds like glucose are made from carbon dioxide and water using this energy. Plants only absorb a small percentage of the Sun’s energy for the process of photosynthesis. The energy is absorbed in chemicals that make up the plants’ cells

Question 17

Can Animals make their own food? .

Answer 17

No - so they have to eat.r

Question 18

Do all cells contain carbon?

Answer 18

Yes All cells - whether animal, plant or bacteria - contain carbon, because they all contain proteins, fats and carbohydrates. Plant cell walls, for example, are made of cellulose - a carbohydrate.

Question 19

what is the carbon cycle?

Answer 19

Carbon is passed from the atmosphere, as carbon dioxide, to living things, passed from one organism to the next in complex molecules, and returned to the atmosphere as carbon dioxide again. This is known as the carbon cycle.

Question 20

What was the first extinct species to have its DNA studied.

Answer 20

A Quagga - The quagga was the first extinct species to have its DNA studied. The results showed that the quagga was not a separate species as had been previously thought, but was a type of zebra.

Question 21

what are the 3 parts of the carbon cycle?

Answer 21

1. Carbon is passed from the atmosphere, as carbon dioxide, to living things,
2. passed from one organism to the next in complex molecules, and
3. returned to the atmosphere as carbon dioxide again. This is known as the carbon cycle.

Question 22

Removing carbon dioxide from the atmosphere

Answer 22

Green plants remove carbon dioxide from the atmosphere by photosynthesis. The carbon becomes part of complex molecules such as proteins, fats and carbohydrates in the plant

Question 23

.Returning carbon dioxide to the atmosphere - this is the 3rd stage of the carbon cycle - how does it happen?

Answer 23

Organisms return carbon dioxide to the atmosphere by respiration. is not just animals that respire. Plants and microorganisms do, too.

Question 24

The second stage of the carbon cycle is Passing carbon from one organism to the next - how does it happen?

Answer 24

When an animal eats a plant, carbon from the plant becomes part of the fats and proteins in the animal. Microorganisms and some animals feed on waste material from animals, and the remains of dead animals and plants. The carbon then becomes part of these microorganisms and detritus feeders.

Question 25

what is Nitrogen fixation ?

Answer 25

Making nitrogen compounds from nitrogen in the air is called nitrogen fixation.

Question 26

Nitrogen fixation happens in three ways - what are they?

Answer 26

1. The energy in lightning splits nitrogen molecules into individual nitrogen atoms. These react with oxygen to form nitrogen oxides. Nitrogen oxides are washed to the ground by rain, where they form nitrates in the soil
2. Nitrogen-fixing bacteria found in the soil and in the root nodules of leguminous plants, such as peas, beans and clover, fix nitrogen gas into nitrogen compounds
3. The Haber process is used by industry to produce ammonia from nitrogen and hydrogen. Ammonia is used to make nitrogen compounds that are used as fertiliser by farmers.

Question 27

How are Nitrogen compounds in living things returned to the soil through?

Answer 27

Nitrogen compounds in living things are returned to the soil through:
excretion and egestion by animals
the decay of dead plants and animals.
Denitrifying bacteria present in soil break down nitrogen compounds and release nitrogen gas into the air.

Question 28

How did life start?

Answer 28

no one was there to record how life began
early Earth was hotter and the atmosphere consisted mostly of carbon dioxide (with other gases such as ammonia and methane).

Question 29

How old is the earth?

Answer 29

it is not possible to be certain how life on Earth began. We do know that the Earth is about 4,500 million years old

Question 30

How long ago did life on earth start?

Answer 30

there is evidence that living things existed on Earth at least 3,500 million years ago

Question 31

what were the conditions like on early Earth ?

Answer 31

early Earth was hotter and the atmosphere consisted mostly of carbon dioxide (with other gases such as ammonia and methane).

Question 32

what is The main theory about how living things developed ?

Answer 32

The main theory is that living things developed from molecules that could replicate, or copy, themselves, rather like DNA does.

Question 33

There are two possible origins for replicating molecules - what are they?

Answer 33

There are two possible origins for these replicating molecules:
they were produced by the conditions on Earth at the time
they came from somewhere else, such as another planet in our Solar System, or further out in space

Question 34

Over many millions of years these molecules joined with other molecules, gradually becoming ?

Answer 34

Over many millions of years these molecules joined with other molecules, becoming gradually more complex and dependent on each other. The process of evolution by natural selection eventually led to all of the different living things that we see on Earth today.

Question 35

Charles Darwin was an ?

Answer 35

Charles Darwin was an English naturalist

Question 36

Charles Darwin explained his ideas on evolution in a book called, ?

Answer 36

He explained his ideas on evolution in a book called, ‘On the Origin of Species’, published in 1859.

Question 37

The basic idea behind the theory of evolution is ?

Answer 37

The basic idea behind the theory of evolution is that all the different species have evolved from simple life forms. These simple life forms first developed more than 3 billion years ago (the Earth is about 4.5 billion years old). - from the first bacteria to the first modern humans.

Question 38

Selective breeding is a process where we choose the ?? .

Answer 38

Selective breeding is a process where we choose the characteristics we want in an animal or plant. We then breed together a male and female showing some of those characteristics. From the offspring produced we select those that show the characteristic the most, and breed them together.

Question 39

What is a Mutation?

Answer 39

Mutations are changes that can occur in genes. These changes are random and can be caused by background radiation and chemicals that we come into contact with, for example the chemicals in cigarette smoke.

Question 40

desribe 4 effects of mutation?

Answer 40

1/ Sometimes these changes can be so severe that the cell dies,

2. sometimes the cell can divide uncontrollably and become cancerous,
3. and sometimes the changes are small and the cell survives.
4. Very rarely the changes may even be beneficial to us and produce new and useful characteristics.

Question 41

If these changes occur in normal body cells, the changes are lost when we die. But if the changes occur in ?? then there is the possibility that the changes in the gene will be passed onto the next generation.

Answer 41

But if the changes occur in our sex cells such as sperm and ova, there is the possibility that the changes in the gene will be passed onto the next generation.

Question 42

what jappens when these changes are passed on to the next generation ?

Answer 42

It is when these changes are passed on to the next generation that natural selection can either ensure that they are selected if they are useful, or disappear from the gene pool if they are not.

Question 43

what causes a New species?

Answer 43

The combined effect of these mutations, environmental changes, and natural selection, can sometimes produce changes in the organism that are so great that a new species is produced. This does not happen very often and only occurs when the mutated organism can no longer breed with the original species and is capable of producing fertile offspring.

Question 44

Darwin was not the only person to develop a theory of evolution. Who developed an alternative theory at the beginning of the 19th century.?

Answer 44

Jean-Baptiste Lamarck was a French scientist who developed an alternative theory at the beginning of the 19th century.

Question 45

what was Lamarck theory

Answer 45

His theory stated that a characteristic which is used more and more by an organism becomes bigger and stronger, and one that is not used eventually disappears. Any feature of an organism that is improved through use is passed to its offspring.

Question 46

what is Selective breeding?

Answer 46

Selective breeding is a process where we choose the characteristics we want in an animal or plant

Question 47

Causes and effects

Mutations are changes that can occur in genes. These changes are random and can be caused by what?

Answer 47

These changes are random and can be caused by background radiation and chemicals that we come into contact with, for example the chemicals in cigarette smoke.

Question 48

how does ‘Passing on’ mutations happen?

Answer 48

Passing on mutations
If these changes occur in normal body cells, the changes are lost when we die. But if the changes occur in our sex cells such as sperm and ova, there is the possibility that the changes in the gene will be passed onto the next generation.
It is when these changes are passed on to the next generation that natural selection can either ensure that they are selected if they are useful, or disappear from the gene pool if they are not.

Question 49

How are New species produced?

Answer 49

New species
The combined effect of these mutations, environmental changes, and natural selection, can sometimes produce changes in the organism that are so great that a new species is produced. This does not happen very often and only occurs when the mutated organism can no longer breed with the original species and is capable of producing fertile offspring.

Question 50

where does Most of the evidence for evolution come from? Name one of the problems of this evidence?

Answer 50

Most of the evidence for evolution comes from the fossil record. Fossils show how much, or how little, organisms have changed over time.
One of the problems with the fossil record is that it contains gaps. Not all organisms fossilise well. And many fossils are destroyed by the movements of the Earth, or have simply not been discovered

Question 51

Describe the case of the peppered moths

Answer 51

Before the Industrial Revolution in Britain, most peppered moths were of the pale variety. They were camouflaged against the pale birch trees they rested on. Moths with a mutant black colouring were spotted easily by birds and eaten. This gave the white variety an advantage, making them more likely to survive and reproduce.
Airborne pollution in industrial areas blackened the birch tree bark with soot. This meant the mutant black moths were now camouflaged, while the white variety became more vulnerable to predators. It gave the black variety an advantage. They were then more likely to survive and reproduce. Over time, the black peppered moths became far more numerous in urban areas than the pale variety

Question 52

Microorganisms such as bacteria and viruses reproduce rapidly and can evolve in a relatively short time. Give one example that is therefore an Antibiotic-resistant bacteria?

Answer 52

One example is the bacterium E. coli.

Question 53

Scientists can now examine the DNA from different species of organism and use the data produced to see how closely related the two species are to each other. By collecting a lot of this data, scientists can compare the results with conventional ideas about how organisms have evolved. What conventional theory does DNA data support?

Answer 53

What they found was that DNA data supported the conventional theory of evolution

Question 54

Describe an explanation that links together things that were previously thought to be unrelated

Answer 54

DNA data being used to support the theory of evolution. Also people had noticed that there was a wide variety of different things living on the planet. Darwin noticed that different islands in the Galapagos had different types of finches adapted to eating the type of food found on each island. It was only when Darwin produced his theory of evolution by natural selection that these two unrelated facts were linked together.

Question 55

why is Extinction is still occurring?

Answer 55

Extinction is still occurring, a lot of it because of human activity. We compete with other living things for space, food and water, and are very successful predators

Question 56

Name one way in which energy is transferred between organisms in an ecosystem and then used for a number of life processes.

Answer 56

In a food chain

Question 57

What percent of the energy in a food chain is passed on to the next level?

Answer 57

only around 10 per cent of the energy is passed on to the next level.

Question 58

How does energy pass out of a food chain?

Answer 58

The rest of the energy passes out of the food chain in a number of ways:
via heat energy
is used for life processes (for example movement)
uneaten parts that pass to decomposers
is excreted and passes to decomposers.
As less energy is transferred at each level of the food chain, the number of organisms at each level gets smaller

Question 59

What are the Key features of the nitrogen cycle?

Answer 59

As a result of the processes, nitrogen is cycled continually through the air, soil and living things. This is called ‘the nitrogen cycle’.

Question 60

How are Antibiotic-resistant strains of bacteria formed?

Answer 60

Its DNA can be damaged or changed during replication, and most of the time this causes the death of the cell. But occasionally the mutation is beneficial (to the bacteria). For example, it may allow resistance to certain antibiotics. When those antibiotics are present, the resistant bacteria have an advantage over the bacteria that are not resistant.

Question 61

What happens when the changes are severe?

Answer 61

Sometimes these changes can be so severe that the cell dies, sometimes the cell can divide uncontrollably and become cancerous, and sometimes the changes are small and the cell survives. Very rarely the changes may even be beneficial to us and produce new and useful characteristics.

Question 62

Lamarck’s theory involved two ideas. What were they?

Answer 62

His theory involved two ideas. These are:
the law of use and disuse
the law of inheritance of acquired characteristics

Question 63

Charles Dawrin studied what ??? during a five-year voyage around the world in the 19th century

Answer 63

who studied variation in plants and animals during a five-year voyage around the world in the 19th century

Question 64

Lamarck’s theory cannot account for all the observations made about life on Earth. For instance, his theory would predict that …… gradually become ….., and ……… organisms disappear. Darwin’s theory can account for the ……………. ………………..of ………… organisms

Answer 64

Lamarck’s theory cannot account for all the observations made about life on Earth. For instance, his theory would predict that all organisms gradually become complex, and simple organisms disappear.

Darwin’s theory can account for the continued presence of simple organisms

Question 65

Most of the evidence for …………………… comes from the fossil record. Fossils show how…., or how little, organisms have ……………. over time.

Answer 65

Most of the evidence for evolution comes from the fossil record. Fossils show how much, or how little, organisms have changed over time.

Question 66

Before the Industrial Revolution in Britain, most peppered moths were of the pale variety. They were camouflaged against the …. birch trees they rested on. Moths with a mutant black colouring were ………. …….. by birds and eaten. This gave the white variety an advantage, making them more likely to survive and reproduce.

Answer 66

Before the Industrial Revolution in Britain, most peppered moths were of the pale variety. They were camouflaged against the …. birch trees they rested on. Moths with a mutant black colouring were ………. …….. by birds and eaten. This gave the white variety an advantage, making them more likely to survive and reproduce.

Question 67

Scientists can now examine the DNA from different species of organism and use the data produced to see ….. …………………………………. By collecting a lot of this data, scientists can compare the results with conventional ideas about how organisms have evolved. What they found was that DNA data ………. the conventional theory of evolution.

Answer 67

Scientists can now examine the DNA from different species of organism and use the data produced to see how closely related the two species are to each other. By collecting a lot of this data, scientists can compare the results with conventional ideas about how organisms have evolved. What they found was that DNA data supported the conventional theory of evolution.

Question 68

Peppered moth: Airborne pollution in industrial areas ………………………the birch tree bark with soot. This meant the ………… …………. moths were now camouflaged, while the white variety became more vulnerable to predators. It gave the black variety an advantage. They were then more likely to survive and…………… Over time, the black peppered moths became far more numerous in urban areas than the pale variety

Answer 68

Peppered moth: Airborne pollution in industrial areas ………………………the birch tree bark with soot. This meant the ………… …………. moths were now camouflaged, while the white variety became more vulnerable to predators. It gave the black variety an advantage. They were then more likely to survive and…………… Over time, the black peppered moths became far more numerous in urban areas than the pale variety

Question 69

Millions of different living things inhabit the Earth. This wide variety of life is called ,,,,,,,,,,,,,,,. This is important and so we must use the Earth in a sustainable way to ensure we maintain a good level of biodivesity in living things and species.

Answer 69

Millions of different living things inhabit the Earth. This wide variety of life is called biodiversity. Biodiversity is important and so we must use the Earth in a sustainable way to ensure we maintain a good level of biodivesity in living things and species.

Question 70

Organisms are classified into different groups. This classification is done according to similarities and differences in characteristics including 2 items - what are they?

Answer 70

Organisms are classified into different groups. This classification is done according to similarities and differences in characteristics including:
physical features
DNA.

Question 71

A large group containing many organisms with a small number of characteristics in common, such as a ………… or
a small group containing fewer organisms with more characteristics in common, such as a…….

Answer 71

large group containing many organisms with a small number of characteristics in common, such as a kingdom
a small group containing fewer organisms with more characteristics in common, such as a species.

Question 72

what is a large group containing many organisms with a small number of characteristics ?
what is a small group containing fewer organisms with more characteristics in common?

Answer 72

large group containing many organisms with a small number of characteristics in common, such as a kingdom
a small group containing fewer organisms with more characteristics in common, such as a species.

Question 73

One of the problems with the fossil record is that it ….. . Not all organisms……………….well. And many fossils are …… by the movements of the Earth, or have simply not been ………………

Answer 73

One of the problems with the fossil record is that it contains gaps. Not all organisms fossilise well. And many fossils are destroyed by the movements of the Earth, or have simply not been discovered.