Cells and Reproduction Homework 1: Microscopes

In science, we often have to look at very small things. Sometimes a hand lens can help us. A hand lens has a magnifying power of 10X which means that we see the object ten times larger than it really is. If the object is too small to be seen with a hand lens then we have to use a microscope.

Microscopes usually have an eyepiece lens and three objective lenses. If you multiply the magnifying power of the eyepiece lens by the magnifying power of the objective lens in use, this gives you the total magnifying power of the microscope.

Magnifying Power = Eyepiece Power X Objective Power

So if you were using an objective lens that was 10X, the magnifying power would be 10 X 10 = 100X. The eyepiece power is usually 10X while the low power objective lens is 4X and the high power lens is 30X.

A microscope must be used to look at cells because they are so small. Cells were discovered in 1665 by the English scientist, Robert Hooke. When he examined the bark of a tree he found that the cork in the bark was made up of hundreds of little boxes which he called cells. It is now known that all living things are made up of cells.

1 Name two instruments, mentioned in the passage, which can be used to look at small organisms.

1

2 Which of these two instruments is more powerful? 1

3 If you saw 8X written on a lens, what would it mean? 1

4 How many lenses does a microscope usually have? 1

5 What would be the magnifying power of the microscope in the passage using:

a) the low power objective lens?

b) the high power objective lens? 2

6 Why is Robert Hooke famous? 1

7 When Robert Hooke looked at the cork, what did he see? 1

8 Where did Robert Hooke get the cork from? 1

9 How many years ago were cells discovered? 1 TOTAL = 10 MARKS

CELLS AND REPRODUCTION: HOMEWORK 2

ChallengeMake a 3D model plant cell using common materials that can be found around the house.

ContentYour model cell should contain the following structures.

cell wall

cell membrane

cytoplasm

nucleus

chloroplasts

vacuole

Your model cell should have all the structures in the

correct place

Your model cell should be colourful

Marks will be awarded for all of the above points

You can use anything you think is suitable but make sure you ask permission before using anything that does not belong to you.

Examples of things you might use include

-plastic bags-plasticene-rubber balls

-sellotape-dried peas-cardboard boxes

-plastic boxes-shoe boxes-coloured paper

-anything else you can think of

Cells and Reproduction Homework 3: Research Exercise

Try to find the answers to the following questions about mothers and children.

You will need to use some of the following resources:-

• Books (eg Guinness Book of World records, encyclopaedia).

• Library (school or public).

• Internet.

1 What is the greatest number of children ever born to one mother? (1)

3 What was the age of the oldest woman ever to have a baby? (1)

4 What are “Siamese twins”? (1)

5 Where does the term ‘Siamese twins’ come from? (1)

6 What are “fraternal twins”? (1)

7 How many babies make up:

a) Quintuplets(1)

b) Sextuplets(1)

8 What is a premature baby?(1)

9 Who was the world’s first ‘test tube’ baby?(1)

TOTAL = 10 MARKS

Cells and Reproduction Homework 4:

DNA Research Exercise

Use the library or internet to answer the following questions.

1When was DNA first isolated?1

2Who discovered the structure of DNA?1

3Who discovered DNA fingerprinting?1

4When was the first DNA fingerprint made?1

5When was DNA fingerprinting first used to convict someone of a crime? 1

6Who was the first person to be convicted of a crime using DNA fingerprint evidence? 1

7Dolly the sheep was the first cloned mammal.

What is a clone?1

8How old was Dolly when she died?1

9Which animal has the most chromosomes in each of its cells?1

10How many chromosomes does this animal have in its cells?1