Name

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Cambridge Secondary 1 Science Topic Book: B7v Variation and classification Bv Variation and classification (UK KS3: 7D, 8D, 9D)

• 7Bv1 Understand what is meant by a species.

• 7Bv2 Investigate variation within a species. Secondary sources can be used.

• 7Bv3 Classify animals and plants into major groups, using some locally occurring examples.

Notebook points

Effort score for word list activities % Word list test score %

Effort score for mind map % Multiple Choice test result %

Effort score for past exam questions % End of topic test %

Overall effort score for this

topic %

Overall grade for

topic %

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Essential Science workbook: Chapter 4 Variation and classification (pages 24 to 26)

Contents Bv Variation and classification (UK KS3: 7D, 8D, 9D) ...................................................................... 1

Essential Science workbook: ................................................................................................................ 2

What you should have done if you wanted the highest grade in this course for this topic: ................. 3

ESSENTIAL INFORMATION Sec1 Sci B7v Variation and Classification Review Pages ................. 8

Mind map TASK .................................................................................................................................... 10

Sec1 Sci B7v WS Introduction to Classification .................................................................................... 11

Task 1 Classifying animals ................................................................................................................. 11

Task 2 Classifying insects .................................................................................................................. 12

Extension tasks 1 – Looking at variation and relationships ................................................................... 14

Extension Task 2: Looking at one variable, height, and investigating the number of students with

certain heights in a single class .............................................................................................................. 15

Extension Task 3: Investigating how physical environmental factors affect the features of an organism

................................................................................................................................................................ 16

Sec1 Sci B7v WS Identifying things using keys .................................................................................... 19

A simple key in action ........................................................................................................................ 19

A key for different plants ....................................................................................................................... 20

Extension work ....................................................................................................................................... 20

Extension work: Animals with Backbones - Vertebrates ....................................................................... 21

Key to identify vertebrates ..................................................................................................................... 21

Now use your key to complete this table................................................................................................ 22

Classifying living things – Introduction ................................................................................................. 23

Classification (biological)Simple English Wikipedia ............................................................................ 24

Homology........................................................................................................................................... 24

Biological classification in action – The Brown Bear ............................................................................ 25

Looking at the highest ranks in the classification of living organisms .............................................. 26

The 5 Kingdoms of life....................................................................................................................... 26

What is a species? ............................................................................................................................... 27

Variations of the same species ........................................................................................................... 28

How are the different organisms of earth related to each other? ............................................................ 32

Sec1 Sci B7v Sample questions 25marks ............................................................................................... 33

Mark Scheme Sec1 Sci B7v Sample questions 25marks ....................................................................... 37

Extension task: Expanding your mind using the B7c Part 2 Cells and Micro-organisms topic ............. 37

Exploring Academic research ............................................................................................................. 39

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What you should have done if you wanted the highest grade in this course for this topic:

1. Complete notes taken from class, which clear headings underlined with a ruler and the date for each

piece of work. All single sheets should be neatly stuck in your book, ideally with clear tape and with the

edges cut off so that they don’t stick our of your book

2. Cornell notes along the side with translations of new English words you don’t understand and a

summary at the bottom of the page that explains in just one sentence what you. Only the very best

students will probably be able to do this properly, but everyone should at least try.

3. Complete the exercises for the word list test you will have in the second week. Remember, when I take

these topic books in, I will check and give you and effort score

4. Compete the mind map based on the review sheets inside this topic book. This will help you to learn for

the multiple choice question test

5. Completed the past exam questions as the back of this topic book to help you prepare for the end of

topic test, which is the most important of the assessed activities you will do.

6. EXTENSION ACTIVITIES: The ablest students will also have completed all of the questions in the

workbook, and in the back of their exercise book, also completed the questions given in the textbook

sections that have been handed out.

7. FOR THE VERY ABLEST STUDENTS: They will also have explored one part of this topic that they find

fascinating and will have either made a poster, or a presentation, e.g. on power point and explained

what they know during a chemistry gifted and talented session, which are open to all students across

grades 6 and 7, and run every Wednesday during prep time 3:45 to 4:30pm in Mr Brannac’s classroom.

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Sec1 Sci B7v WL Variation and classification 24CORE words

# Difficulty English Chinese Meaning in English Meaning in Chinese

1 Core Amphibian 两栖动物 Vertebrate with moist skin, e.g. a frog. 具有湿润皮肤的脊椎动物，例如一个青蛙。

2 Core Animal

kingdom 动物王国

The group of organisms that contains all vertebrates and invertebrates.

包含所有脊椎动物和无脊椎动物的生物群。

3 Core Arthropod 节肢动物 Invertebrate that has jointed legs, e.g. fly,

spider. 无脊椎动物，有腿，例如飞，蜘蛛。

4 Core Backbone 骨干

A collection of bones that join together to protect the nerves in the back of animals

that allow its brain to communicate with the muscles.

一组骨头连接在一起，以保护动物背部的神

经，使其大脑与肌肉交流。

5 Core Bird 鸟 Vertebrate with feathers, e.g. an eagle. 带有羽毛的脊椎动物，例如一只鹰。

6 Core Classification 分类 Sorting things into groups. 将事物分组。

7 Core Environment 环境 The conditions around an organism caused

by physical environmental factors. 由物理环境因素引起的有机体周围的条件。

8 Core Fish 鱼 Vertebrate with wet scales that lives in the

water, e.g. salmon.

具有生活在水中的湿鳞的脊椎动物，例如三

文鱼。

9 Core Feather 羽毛 A type of low density covering that helps

birds stay warm and fly

一种低密度的覆盖物，可以帮助鸟类保持温

暖和飞行

10 Core Hair 头发 A type of long thin covering that helps

mammals stay warm

一种长薄的覆盖物，可以帮助哺乳动物保持

温暖

11 Core Head 头 Front or top end of an animal’s body. 动物身体的前端或顶端。

12 Core Inherited variation

继承的变

异

Differences between organisms passed to organisms by their parents in reproduction.

生物体在繁殖过程中传给生物体的差异。

13 Core Insect 昆虫 Type of arthropod with three pairs of legs,

e.g. a fly.

具有三对腿的节肢动物的类型，例如一只苍

蝇。

14 Core Invertebrate 无脊椎动物 Animal with no backbone. 没有骨干的动物。

15 Core Kingdom 王国

Largest groups that living things are sorted into. The two biggest are those that group all

the plants together and the other that groups all of the animals together.

生物被分类的最大群体。最大的两个是将所

有植物组合在一起的那个，另一个将所有动

物组合在一起。

16 Core Mammal 哺乳动物 Vertebrate with hair and produces milk, e.g.

human. 用头发脊椎动物并产生牛奶，例如人类。

17 Core Milk 牛奶 This liquid is food for the offspring of all

mamals and produced by the mother

这种液体是所有母亲的后代的食物，由母亲

生产

18 Core Offspring 子孙 Any plant or animal formed by reproduction.

They are produced by their parents.

通过繁殖形成的任何植物或动物。它们是由

父母制作的。

19 Core Organism 生物 A living thing. 生物。

20 Core Plant

kingdom 植物王国

Group of organisms that are able to produce their own food and have specialised cells.

能够生产自己的食物并具有特化细胞的生物

群。

21 Core Reptile 爬虫 Vertebrate with dry scales, e.g. a snake. 具有干鳞的脊椎动物，例如一条蛇。

22 Core Scales 秤 Some animals like fish are covered in these

hard plates 这些坚硬的盘子覆盖了像鱼这样的动物

23 Core Species 种类 A group of organisms that can reproduce with each other to produce offspring that

will also be able to reproduce.

一组生物体，可以相互繁殖，生产出能够繁

殖的后代。

24 Core Vertebrate 脊椎动物 An animal with a backbone. 有骨干的动物。

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Fill in the missing keyword: Circle the words you knew without looking at the word list at the front

English Meaning in English

Head Front or top end of an animal’s body.

Organism A living thing.

Species A group of organisms that can reproduce with each other to produce offspring that will also be

able to reproduce.

Vertebrate An animal with a backbone.

Plant kingdom Group of organisms that are able to produce their own food and have specialised cells.

Fish Vertebrate with wet scales that lives in the water, e.g. salmon.

Feather A type of low density covering that helps birds stay warm and fly

Invertebrate Animal with no backbone.

Inherited variation

Differences between organisms passed to organisms by their parents in reproduction.

Environment The conditions around an organism caused by physical environmental factors.

Insect Type of arthropod with three pairs of legs, e.g. a fly.

Kingdom Largest groups that living things are sorted into. The two biggest are those that group all the

plants together and the other that groups all of the animals together.

Milk This liquid is food for the offspring of all mammals and produced by the mother

Animal kingdom The group of organisms that contains all vertebrates and invertebrates.

Classification Sorting things into groups.

Hair A type of long thin covering that helps mammals stay warm

Arthropod Invertebrate that has jointed legs, e.g. fly, spider.

Offspring Any plant or animal formed by reproduction. They are produced by their parents.

Mammal Vertebrate with hair and produces milk, e.g. human.

Reptile Vertebrate with dry scales, e.g. a snake.

Scales Some animals like fish are covered in these hard plates

Backbone A collection of bones that join together to protect the nerves in the back of animals that allow its

brain to communicate with the muscles.

Bird Vertebrate with feathers, e.g. an eagle.

Amphibian Vertebrate with moist skin, e.g. a frog.

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Fill in the missing meaning: Circle the words you knew without looking at the word list at the front

English Meaning in English

Inherited variation

Differences between organisms passed to organisms by their parents in reproduction.

Scales Some animals like fish are covered in these hard plates

Hair A type of long thin covering that helps mammals stay warm

Backbone A collection of bones that join together to protect the nerves in the back of animals that allow its

brain to communicate with the muscles.

Vertebrate An animal with a backbone.

Animal kingdom The group of organisms that contains all vertebrates and invertebrates.

Organism A living thing.

Amphibian Vertebrate with moist skin, e.g. a frog.

Classification Sorting things into groups.

Fish Vertebrate with wet scales that lives in the water, e.g. salmon.

Environment The conditions around an organism caused by physical environmental factors.

Mammal Vertebrate with hair and produces milk, e.g. human.

Offspring Any plant or animal formed by reproduction. They are produced by their parents.

Plant kingdom Group of organisms that are able to produce their own food and have specialised cells.

Head Front or top end of an animal’s body.

Feather A type of low density covering that helps birds stay warm and fly

Invertebrate Animal with no backbone.

Reptile Vertebrate with dry scales, e.g. a snake.

Insect Type of arthropod with three pairs of legs, e.g. a fly.

Species A group of organisms that can reproduce with each other to produce offspring that will also be able

to reproduce.

Milk This liquid is food for the offspring of all mammals and produced by the mother

Bird Vertebrate with feathers, e.g. an eagle.

Kingdom Largest groups that living things are sorted into. The two biggest are those that group all the plants

together and the other that groups all of the animals together.

Arthropod Invertebrate that has jointed legs, e.g. fly, spider.

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ESSENTIAL INFORMATION Sec1 Sci B7v Variation and Classification Review Pages

Variation A species is a group of organisms that can reproduce with one another to produce offspring that will also be able to reproduce. The differences between organisms are known as variation. There is variation between different species and between members of the same species.

There is variation between different species. Lions and tigers are different species. Tigers have stripes, lions do not.

There is variation between members of the same species. All tigers have different patterns of stripes.

Sometimes there is a relationship or correlation between two features. A relationship is normally best shown on a line graph. The line will go steadily up or steadily down. Variation can have environmental or inherited causes.

Relationship: people with longer arms have longer middle fingers.

Environmental variation An organism’s surroundings are known as its environment. The conditions in an environment are called environmental factors. Plants are affected by environmental factors like the amount of light, the amount of water, the amount of warmth and the amount of mineral salts in the soil.

The cress seedlings on the left have not had enough light. The plant on the left has not had enough water. It has wilted.

Animals are also affected by environmental factors. Humans who get sunburnt or have scars are examples.

Inherited variation This is caused by features being passed from parents to their offspring. In humans, natural eye colour and natural hair colour are both examples of inherited variation.

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Classification There are so many species that we need to put them into groups. This is called classification. The first set of groups that organisms are divided into are called kingdoms. The two largest kingdoms are the plant kingdom and the animal kingdom. The main difference between these two kingdoms is that plants can make their own food and animals cannot. The animal kingdom is divided into other groups. The vertebrates are animals that have a backbone. There are five sorts of vertebrate. There are another eight groups which are all invertebrates. The most important groups to know about are in bold type.

The plant kingdom is also divided into groups.

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Mind map TASK Using your notes, the information contained in the word lists, the past exam questions and in this topic book (and any extra information you may have discovered in your own research along the way) create a mind map in the space below

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Sec1 Sci B7v WS Introduction to Classification Task 1 Classifying animals Look at the pictures of different animals found on a farm and count the different numbers to complete the tasks below

1 A scientist has been making a study of the farm. Make a table and fill it in using the picture

above. 2 Draw a bar chart IN PENCIL to show how many animals of each species there are on the farm.

Remember to label the axis!

Type of animal Number of different kinds

Bar Chart

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Task 2 Classifying insects Look carefully at insects on the next page. 1 Which features vary (are different)? There are four.

i _______________________________ iii _______________________________

ii _______________________________ iv _______________________________

2 Fill in the table below to show the eye colours and number of stripes.

Number of insects with black eyes and more than

five stripes

Number of insects with black eyes and less than

five stripes

Number of insects with WHITE eyes and more

than five stripes

Number of insects with WHITE eyes and less than

five stripes

A B C D

3 On the grid below, draw a bar chart to show this information. Remember to use as much of the

graph area as possible and to label your axis!

4 What is the relationship shown in the graph? ______________________________________ ___________________________________________________________________________

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Extension tasks 1 – Looking at variation and relationships Using complete sentences answer these questions about the insects on the previous page 1 Which features vary? 2 These insects are all the same species. What does this mean? 3 There is a relationship between some of these variations. What do we mean by the word

‘relationship’ in this case? 4 Draw a table of the data and a graph to show the relationship between the length of the

abdomen and the width of the head. Use the table template as a guide

Insect #

Length of Abdomen/mm

Width of head/mm

5 Write down one sentence saying what the

relationship between length of abdomen and width of head is.

6 Looking at the insects, find one more relationship. Write down the relationship. 7 Would you show this relationship using a line graph or a bar chart? Explain your reasoning.

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Extension Task 2: Looking at one variable, height, and investigating the number of students with certain heights in a single class Table 1 shows the heights of a class of students. In Table 2, the heights have been divided into groups, 150–154 cm, 155–159 cm etc.

Heights of class 8b (cm)

160 161 169 183 152

169 180 151 159 172

174 187 167 177 177

155 164 166 168 170

160

Table 1

Height groups (cm) Number of pupils in each height group

150–154 2

155–159

Table 2

1 Use the information in Table 1 to complete Table 2. 2 Draw a bar chart to show this information. Label the axes.

3 a What shape is your chart overall?

b What sort of distribution does your chart show?

4 a Which type of variation do the heights show; continuous or discontinuous?

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b How can you tell this?

c Name one human feature which shows the other type of variation.

5 What do you think is responsible for how tall a person grows?

Extension Task 3: Investigating how physical environmental factors affect the features of an organism Oxygen dissolves in water. Fish absorb this dissolved oxygen using gills. If you look carefully at a fish you can see the gills moving. Look at the graphs below.

1 What relationship do each of the graphs show? 2 a What is the relationship between the amount of oxygen dissolved and the number of gill

movements per minute?

b Sketch a graph for this relationship using the axis below. Label them, using “Oxygen dissolved in 1litre (mg)” along the x axis

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Look at the pictures of the fish. Some of these fish are the same species and others are different species.

3 What is a species? 4 Which fish are the same species? 5 What variations can you see between the different species? 6 What variations can you see between members of the same species? 7 a For the fish which are like Fish 3, what is the relationship between the number of spots on

the tail and the length of the body?

b Measure the lengths of the bodies and plot the relationship with the number of spots on the tail on a suitable chart or graph.

Fish # Number of spots on tail

Length of body/mm

c Do you think that you can safely say that

this relationship will be true for all fish of this type? Explain your answer.

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8 For each of the other two species of fish find one further relationship and one example of features that are not linked.

9 Very rarely members of different species can breed. The offspring are called hybrids. Draw a

picture of what a hybrid of Fish 1 and Fish 3 would look like. 10 Name one other hybrid animal and say what its parents are. 11 What can hybrids not do that their parents can?

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Sec1 Sci B7v WS Identifying things using keys

A classification key is a series of questions about the organism's physical characteristics. The answers will either

branch off to another question or will identify your unknown organism. classification keys. Identify unknown

organisms. It's important to look very carefully at what you've found. You can use classification keys for

anything, not just living things.

A simple key in action

Work in pairs.

Player 1: Look at the vehicles above and chose one

Player 2: Ask the following questions in turn until you can identify the vehicle player 1 has chosen.

1 Does the vehicle have any wheels?

▪ If the answer is YES, go to question 3. If the answer is NO, go to question 2

2 Does it have wings?

▪ If the answer is YES, it is an Aeroplane.

▪ If the answer is NO, it is a Boat.

3 Does the vehicle have 2 wheels only?

▪ If the answer is YES, it is a Bike.

▪ If the answer is NO, it could be a Car.

These are not the only questions that could have been asked – can you think of another group that could be used to identify the same vehicles? Write your answer below:

This is only a small key and cannot identify more than the four vehicles. To identify more objects, you need a longer set of questions.

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Keys can be shown as a flow diagram:

A key for different plants Look at the different kinds of plants below and try to think of a key like the one shown to you that would allow you to always identify one, and only one of these plants Write your key in your

A - Oak Tree B – Strawberry plant C – Apple tree D - Rose

E – Blackberry plant F - Dandelions G - Grass H – Palm tree

Test your key out with your partner and see if it always works.

Extension work 1. Create the smallest possible key for all of the plants, then try to write it out as a flow diagram as shown at the top of

this page 2. Is there a particularly effective type of question? If so what are its characteristics? Write out what you have found

out after your flow diagram

Does the vehicle have any wheels?

YesDoes it have 2 wheels only?

Yes. It is a bike

No. It is a car

NoDoes it have

wings?

Yes. It is a plane

No. It is a boat

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Extension work: Animals with Backbones - Vertebrates Create a key in the space below to separate the animals shown on the next page into the right group (called phylum). Chose one animal from each type of vertibrate

Vertebrate Characteristics

Fish Live in water, moist skin covered with scales, breathe using gills, move using fins, lay eggs in water.

Amphibians Moist skin without scales, four limbs but spend a large part of life in water, lay eggs in water where young develop.

Reptiles Four limbs at an angle to the body, dry skin with scales, lay eggs with a leathery shell often protected in a nest.

Birds Two limbs adapted as wings, fly, lay hard shelled eggs in a nest, feed with a beak, maintain a high body temperature.

Mammals Body covered with hair, maintain a warm body temperature, have live young feed on milk from mammary glands, external ears.

Key to identify vertebrates

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Now use your key to complete this table. From: https://www.researchgate.net/figure/A-phylogenetic-tree-of-a-broad-selection-of-jawed-vertebrates-shows-that-

lungfish-not_fig3_236227537

Animal Vertebrate phylum Animal Vertebrate phylum

Dog Mammal Mammal

Pufferfish Fish Reptile

Turkey Bird

Tilipia Elephant shark

Chinese brown frog Bird

Elephant Fish

This tree shows the relatedness of each species to each other. In your exercise books, state which species is most closely related to humans? Which species if furthest away (least related) from us? Is there a way you can tell how closely related a specie is to another? Research “most recent common ancestor”.

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Additional Extension information Classifying living things – Introduction NOTE: The words and keywords used in this text that are not included in the word list are not needed to score 80 or 90% on the test, but they are needed to give you a deeper understanding, which is why they have been included. Science is about studying our universe in a very special way, it is not the only way to understand our

experiences or our universe, but it is always the best way to get reproducible results. This means it is

the best way to make predictions, which is essential if you are going to invent anything from

computers to modern medicine, you want to know that your device or medicine will always work in a

particular way. A modern smartphone will have thousands of different parts, if anyone of them

stopped working in a predictable way, your new phone probably would not work at all.

Biology could not exist as a science if you were not able to identify clearly which organism you were

describing and investigating. It would be useless to say compare how fast animal A can run compared

to animal B if animal A was a fish. Classification helps us understand exactly which animal someone is

talking about, and helps us understand how different, but closely related animals are similar and

different to each other.

Ultimately, by understanding the relationships between different animals and plants Charles Darwin

was able to suggest a way that evolution might be able to explain all of the variation we see in all of

life. This new theory, Natural Selection, could only exist if Darwin was able to explain to himself and

others, that he was studying certain specific species of organisms. The most famous of his

investigations were a type of bird called a finch.

The differences and similarities between these closely related species forced Darwin to discover

natural selection, but he was not the only person to discover it, Alfred Russell Wallace also discovered

the same idea. This has happened before in science, and it is a natural product of the scientific

method.

These birds are all different species, but very closely related. For more information about variation in

these birds see here:

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https://www.mun.ca/biology/scarr/Adaptation_in_Darwins_Finches.html

Classification (biological)Simple English Wikipedia From Wikipedia, the free encyclopedia

https://simple.wikipedia.org/wiki/Biological_classification

A hierarchy of important ranks

Biological classification is how biologists group organisms.

The classification has its root in the work of Aristotle who invented a multi-ranked system. A great influence was Carolus Linnaeus, who popularized the idea of binomial nomenclature using a two-part name indicating the genus, and the species. The human species is named Homo sapiens. Names of species are often printed in italics, although there is no obligation to do so (this also goes for names of genera, etc., etc.)

Biological classification is also known as taxonomy. It is a science, and like most sciences has evolved over time. At various times different principles were adopted, and it is not rare for different scientists to use different methods. Since the early 20th century, groupings are supposed to fit the Darwinian principle of common descent. These days, molecular evolution studies, which use DNA sequence analysis as data, are popular. This is often called "phylogenetics", a branch or form of cladism. This approach creates an evolutionary Tree of life (biology) and uses characters (traits) to decide on the branches of the taxonomy.

Sometimes organisms placed in the same group (taxon) are similar; such similarity is not necessarity coincidence. It may be the result of shared descent from a common ancestor.[1]

Homology

Homologous traits are similarities caused by common ancestry. They are distinct from traits that are analogous. For example, birds and bats both have the power of flight, but this is not used to classify them together, because it is not inherited from a common ancestor.

In spite of all the other differences between them, the fact that bats and whales both feed their young on milk is one of the features used to classify both as mammals, since it was inherited from a common ancestor.

When the present system of naming living things was developed, Latin was the language most widely used around the world. So, such names are still in Latin. The official descriptions and diagnoses of new taxa in Latin were and are written in Latin as well. Zoologist allow any language for the description of animals. From January 1, 2012, new taxa of algae, fungi and plants may be described in either English or Latin.[2]

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Biological classification in action – The Brown Bear

Kingdom (Animal)

Phylum (Vertebrates: animals with backbones)

Class (Mammals)

Order (Carnivores:

eat meat)

Family (Bear)

Genus (Ursus: the 4

biggest bears)

Species (Brown Bear)

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Looking at the highest ranks in the classification of living organisms

For more information look here: https://en.wikipedia.org/wiki/Phylogenetic_tree

The 3 domains above include all life known to exist but divides it into 3 fundamentally different categories called DOMAINS. All of these life forms, however, are thought to have evolved from the same common single celled ancestor nearly 4 BILLION years ago, which is shown above as start of the main trunk of the tree of life.

The 5 Kingdoms of life This tree shows the variety and importantly the similarities and connectedness of life. The species of organisms that are a little like 2 or more kingdoms are some of the most interesting. This picturte shows very nicely how blurry the boundaries are, and how odd and unrelated some of the organsims of the protista are to each other.

For more information on the history and evolution of the ideas on classification look here: https://en.wikipedia.org/wiki/Kingdom_(biology)

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What is a species? Humans are all from the same species because all healthy humans are able to reproduce with each other, no matter how different they may look, to create offspring that are also able to reproduce. This is the definition of a species that most biologists will use today. All of our closest relatives are different to each other, and us, because they cannot successfully reproduce with each other. Different species of the same family, HOMINIDS, OR Apes:

Homo Sapiens (“wise man” in Latin) are the last of our closest relatives to survive, our next closest relative is our cousin, the chimpanzee:

Individuals of the same species have a variety of differences, but because nearly all of their genes,

which is information that is stored inside your DNA, are the same, they are able to create offspring

that will be a little like both parents, but not exactly like either. This is essential to help speed up

evolution and allows organisms like plants and animals which both usually need two parents to

produce offspring, to adapt more quickly and become more complex than organisms that are able to

reproduce individually, like many bacteria and some yeast micro-organisms.

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Variations of the same species These dogs look very different and have a variety of very different characteristics, but they can all breed together to produce offspring that can also reproduce. All of these dogs are variations within the same species, which is descended from an ancestor of the modern wolf

What is variation?

From: https://www.bbc.com/bitesize/guides/z9gk87h/revision/1

All people are human. They belong to the same species. Your friends and classmates may have

different eye colour and hair colour. Some will be boys and some will be girls. Some will be tall and

some will be shorter. The presence of differences between living things of the same species is

called variation.

Variation between different species is usually greater than the variation within a species.

Inherited and environmental variation Some variation within a species is inherited, and some variation is due to the environment.

Inherited causes of variation Variation in a characteristic that is a result of genetic information from the parents is called inherited

variation.

Children usually look a little like their father, and a little like their mother, but they will not be

identical to either of their parents. This is because they get half of their DNA and inherited features

from each parent.

Each egg cell and each sperm cell contains half of the genetic information needed for an individual.

When these join at fertilisation a new cell is formed with all the genetic information needed for an

individual.

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Here are some examples of inherited variation in humans:

• eye colour

• hair colour

• skin colour

• lobed or lobeless ears

• ability to roll your tongue

•

Eye colour is an example of inherited variation Having lobed or lobeless ears is an example

of inherited variation

Gender is inherited variation too, because whether you are male or female is a result of the genes you

inherited from your parents.

Environmental causes of variation Characteristics of animal and plant species can be affected by factors such as:

• climate

• diet

• accidents

• culture

• lifestyle

For example, you will become heavier if you eat too much food, and you will become lighter if you eat

too little. A plant in the shade of a big tree will grow taller as it tries to reach more light.

Variation caused by the surroundings is called environmental variation. Here are some other examples

of features that show environmental variation:

• your language

• your religion

• flower colour in hydrangeas (these plants produce blue flowers in acidic soil and pink flowers in alkaline

soil)

Inherited and environmental causes Some features vary because of a mixture of inherited causes and environmental causes. For example,

identical twins inherit exactly the same features from their parents. However, if you take a pair of

twins, and twin 'A' is given more to eat than twin 'B', twin 'A' is likely to end up heavier. Weight and

height are common examples of characteristics that are influenced by both genetic and environmental

factors.

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Continuous and discontinuous variation Some of the features of the different organisms in a species show continuous variation, and some

features show discontinuous variation.

Continuous variation Human height is an example of continuous variation. It ranges from that of the shortest person in the

world to that of the tallest person. Any height is possible between these values. So it is continuous

variation.

For any species a characteristic that changes gradually over a range of values shows continuous

variation. Examples of such characteristics are:

• height

• weight

If you record the heights of a group of people and draw a graph of your results, it usually looks

something like this:

A bar chart to represent variation in height

The more people you measure, and the smaller the categories you use, the closer the results will be to

the curved line. This shape of graph is typical of a feature with continuous variation. Weight would

give a graph similar in shape to this.

Discontinuous variation A characteristic of any species with only a limited number of possible values shows discontinuous

variation. Human blood group is an example of discontinuous variation. In the ABO blood group

system, only four blood groups are possible (A, B, AB or O). There are no values in between, so this is

discontinuous variation.

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Here are some examples:

• blood group

• gender (male or female)

• eye colour

A bar chart to represent the frequency of each blood group in the population

Name

Patrick Brannac www.SmashingScience.org Page 32 of 39

How are the different organisms of earth related to each other?

Name

Patrick Brannac www.SmashingScience.org Page 33 of 39

Sec1 Sci B7v Sample questions 25marks 1 Look at these drawings of animals.

a Circle the drawings of invertebrates.

[1 mark] b Complete the sentences to give two differences between a chicken and a fish.

i Chickens have wings, fish have _______________________________________

ii Chickens have feathers, fish have ______________________________________

[1 mark] c Describe one difference between the two fish shown in the drawings.

______________________________________________________________________

[1 mark] 2 Look at this graph.

What relationship does the graph show? __________________________________________ ___________________________________________________________________________

[1 mark] 3 Sandra took cuttings from an African violet plant and put them into pots. She had so many that she had to put them on different windowsills in her house. She ran out of

soil and so some plants were put in different types of soil. She expected all the plants to be identical but some were taller and some had more leaves than others.

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a Give four environmental factors that might have affected the growth of her plants.

i __________________________________________________________________

ii __________________________________________________________________

iii __________________________________________________________________

iv __________________________________________________________________

[2 marks] 4 Look at these pictures of invertebrates. Write the name of the invertebrate group that each

animal is in.

[1 mark] 5 From the following lists of words, circle the words or phrases: a that describe groups which insects belong to.

animal vertebrate plant invertebrate

mollusc arachnid arthropod

b that are features of all insects. backbone jointed legs two body sections

six legs exoskeleton warm-blooded

[3 marks] 6 Look at these pictures of vertebrates. Write the name of the vertebrate group that each animal

is in. The first one has been done for you.

Mammal

[2 marks] 7 Write down two ways in which mammals are different from all other vertebrates.

i ______________________________________________________________________

ii ______________________________________________________________________

[2 marks]

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8 Here is a list of human variations. Fill in the table to show which are caused by inherited factors, environmental factors or both. being sunburnt natural eye colour weight natural hair colour speaking French your accent

Caused only by inherited factors

Caused only by environmental factors

Caused by both inherited and environmental factors

9 Read the following extracts from field guides. For each extract write down what kind of the five types of vertebrate is being described and why you think this.

a Kind of vertebrate ___________________________________________________________ Why you think this ___________________________________________________________

[1 mark]

b

Kind of vertebrate ___________________________________________________________ Why you think this ___________________________________________________________

[1 mark]

c Kind of vertebrate ___________________________________________________________ Why you think this ___________________________________________________________

[1 mark]

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10 Look at these drawings of tracks left by animals. Design a way of classifying them, by completing the branching diagram below. There are two large groups, each of which contains two smaller groups.

[4 marks]

11 Look at this graph. What sort of variation does this graph show? ______________________

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Mark Scheme Sec1 Sci B7v Sample questions 25marks

Question Level Answers Mark scheme

1 5 a Earthworm and spider circled 1 mark – 12 mark for each

3 b i fins; ii scales. 1 mark – 12 mark for each

3 c number of spines 1 mark

2 4 The more fertiliser added, the taller the sunflowers

1 mark

3 6 Four from: light/water/warmth/mineral salts/fertilisers in soil.

2 marks – 12 mark for each one correct

4 5 scorpion – arthropod; fly – insect 1 mark – 12 mark for each one correct.

5 7 a animal, invertebrate, arthropod

b jointed legs, six legs, exoskeleton 3 marks –

12 mark for each one correct.

6 5 Amphibian; fish; mammal; reptile 2 marks – 12 mark for each one correct.

7 5 Any two of: has hair, gives birth to live young, produces milk

2 marks – 1 mark for each one correct.

8 5 a Environmental: being sunburnt, your accent, speaking French

Inherited: natural hair colour, natural eye colour

Both: weight

3 marks – 12 mark for each one correct

9 5 a mammal; has hair 1 mark – 12 mark for each part correct

5 b reptile; dry scaly skin 1 mark – 12 mark for each part correct

5 c amphibian; jelly-coated eggs laid in water

1 mark – 12 mark for each part correct

10 6 Groups: tracks with each part a different size; track with more than two parts to them; track with four toes; tracks with five toes

There are other possibilities which are also valid.

4 marks – 1 for each correct.

11 7 Discontinuous variation 1 mark

Extension task: Expanding your mind using the B7c Part 2 Cells and Micro-organisms topic Use the information below to create a 2 to 5 minute power point presentation, or poster, to explain something that really interests you about this topic. There will be a special extra session in the last week or this topic, or the first week of the next topic when you can explain to others your idea.

• Only students who are really interested in becoming the best at science need to try this, it is up to you if

you want to give it a go. All students in any teaching group are welcome to try though.

• Try to include colorful pictures, especially ones you have drawn yourself, they will make your project

much better than simply copying and pasting from the internet.

• Include lots of details.

• Explaining one thing clearly is much better than just stating many facts.

• Ask a science teacher for help if you want more information about how to do a great presentation, or

Patrick Brannac www.SmashingScience.org Page 38 of 39

about the idea you are interested in. Mr Brannac especially is most interested in any question you have

that he cannot answer!

Who what and where were the first humans? Read more here: Reading level: So-so https://www.sciencenewsforstudents.org/article/where-do-humans-come Reading level: Hard https://www.bbc.com/news/science-environment-47873072 Reading level: Very hard https://www.washingtonpost.com/science/2019/04/10/bones-discovered-an-island-cave-may-be-new-human-species/?utm_term=.cbaab5ebae76

Charles Darwin and Alfred Russel Wallace “On résiste à l'invasion des armées; on ne résiste pas à l'invasion des idées.” Loosely translated as “Nothing is as powerful as an idea whose time has come.” from Victor Hugo, see Wikiqoute here: https://en.wikiquote.org/wiki/Victor_Hugo Both Darwin and Wallace published their theory of Natural Selection at the same time, although Darwin had been working on it for longer. Like most great ideas, it seems that it’s time had come, and if these two scientists didn’t explain evolution using the mechanism of natural selection, another scientist would have. The amount of evidence that was building up in the scientific world was forcing this breakthrough to happen, much like water building up behind a dam. You could investigate either of these scientists. Most thoughtful people would say that Darwin was a good man, not just a great man. Wallace, however, was much more controversial .

http://www.nhm.ac.uk/discover/who-was-alfred-russel-wallace.html For more information on Darwin: http://www.nhm.ac.uk/discover/charles-darwin-most-famous-biologist.html For another view on how living things came to be you could investigate Creationism: https://simple.wikipedia.org/wiki/Creationism which is very similar, in terms of science, to those people who still believe that the world is flat: https://simple.wikipedia.org/wiki/Flat_Earth Many scientists take it for granted that these alternative ideas are wrong, but very few can explain properly why.

Extra information to help you get ideas is available here: Extension links, activities and simulations For this interesting model of how genes work in bacteria click below: https://phet.colorado.edu/en/simulation/legacy/gene-machine-lac-operon

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Simple Wikipedia This uses simpler English words in its articles. It is still run by the same non-profit foundation as Wikipedia, but you might find it easier to read Homepage is: https://simple.wikipedia.org/wiki/Main_Page All things evolve, including logos! Read more here: https://www.strawberrytoo.co.uk/blog-post/the-

evolution-of-logos

For up to date news on science in general For interested but less able students: https://www.dogonews.com/category/science For more able students: https://www.sciencenewsforstudents.org/

ONLY for the most interested and ablest students: For interested but less able students: https://www.dogonews.com/category/science For more able students: https://www.sciencenewsforstudents.org/

Exploring Academic research You don’t need to understand really what is going on in the links below, but just having a look at what scientists actually produce, and make available online for free, can sometimes be an amazing experience.

Genomes OnLine Database (GOLD) This is one place where a lot DNA sequencing information is stored. It is free to use, and is a little like Wikipedia for DNA A scientific article on GOLD: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3245063/ The database itself: https://gold.jgi.doe.gov/index

Foldit A game where you help solve puzzles relating to how proteins are folded. It uses a very rare type of engine, the human brain, to investigate problems that computers are extremely bad as solving, to help scientists to better understand one of the most important questions in biology, how does the DNA sequence eventually become a fully functioning molecular machine (the folded protein). Website: https://fold.it/portal/ The science behind it: https://fold.it/portal/info/science Download: https://fold.it/portal/download/windows