UNIT 1 - Cells (1)

Question 1

You are provided with a thin strip of onion tissue.

Describe how you would prepare a microscope slide of this tissue.
2 marks

Answer 1

1. Put onion tissue on a slide
2. Add iodine solution to stain organelles
3. Apply cover slip
4. Place on stage and secure with stage clips

Question 2

Explain why the tissue needs to be thin. (1 mark)

Answer 2

To allow the light source to illuminate the specimen your observing.

Question 3

Suggest why dye should be added to the onion tissue. (1 mark)

Answer 3

To stain the organelles so you can study them, as the iodine solution allows you to identify the organelles easily.

Question 4

Give one reason why the low power objective lens should be used first when viewing cells. (1 mark)

Answer 4

To get an overall view of the tissue and to identify the specimen you want to study.

Question 5

What is a cell wall made of? (1 mark)

Answer 5

Cellulose

Question 6

What is the name given to a group of cells working together? (1 mark)

Answer 6

A tissue

Question 7

What is an organ? (1 mark)

Answer 7

Multiple different tissues working together to carry out a bodily function.

Question 8

Name one disease caused by bacteria. (1 mark)

Answer 8

Salmonella food poisoning

Question 9

Bacteria cells do not have a nucleus, but they still have genetic material.

Where is the genetic material located? (1 mark)

What shape or form does this genetic material take? (1 mark)

Answer 9

In the cytoplasm in the cell.

A loop of genetic material.

Question 10

Whales are adapted for life in the sea.

Give one feature which is an adaptation to movement in the sea. (1 mark)

Answer 10

A whale fin to propel itself through the water.

Question 11

Give two features of mammals. (2 marks)

Answer 11

Feature = Something you can see

1. Live births
2. Usually have a fur coat or body hair

Question 12

Name the structures found in the nucleus which,

are short lengths of DNA which code for one characteristic (1 mark)

are long lengths of DNA which code for many characteristics (1 mark)

Answer 12

Genes

Chromosomes

Question 13

Describe the function of the cell membrane and explain how it is adapted for this function. (2 marks)

Answer 13

Function - To allow the entry and exit of certain substances.

Adaption - It is selectively permeable so only some substances can enter.

Question 14

What are stem cells? (1 mark)

Answer 14

They are unspecialised cells which can differentiate into any of the specialised cells.

Question 15

Where do stem cells come from? (2 marks)

Answer 15

They are found in a young developing embryo, umbilical cord blood and in adult bone marrow.

Question 16

Why is there controversy about using embryonic stem cells? (1 mark)

Answer 16

As they are seen to cross some ethnically boundaries and are controversial as some people say scientists are trying to ‘play God’.

Question 17

What are the characteristics of living things? (2 marks)

Answer 17

MRS NERG

Movement
Respiration
Sensitivity
Nutrition
Excretion
Reproduction 
Growth

Question 18

How do plants grow? (1 mark)

Answer 18

Mainly by cell extension/elongation, plants have an area at the top (Meristem) = Cell division. An area of elongation below that and finally a zone for differentiation for cells.

Question 19

Write down the definition for Diffusion. (2 marks)

Answer 19

Diffusion is the random movement of particles form a region of high concentration to a region of low concentration along a concentration gradient.

Diffusion is a passive process (No energy required).

Can be demonstrated by putting potassium permanganate into a beaker of water and watch it distribute throughout the beaker.

Diffusion - Osmosis

E.g: Gas exchange between alveoli and lungs, to blood.

Question 20

Name one experiment that describes selectively permeable. (1 mark)

Answer 20

Visking Tubing

Bag of water in a bowl of highly concentrated sugar-water.
Water moves out of the tube by diffusion.

Question 21

List the levels of organisation in increasing size.

Answer 21

Cell –> Tissue –> Organ –> Organ System –> Organsim

Question 22

Stem Cells divide by _______. (1 mark)

Answer 22

Mitosis

Question 23

Why do scientists usually use embryonic stem cells over ones located in adult bone marrow? (2 marks)

Answer 23

They are easier to retrieve and they have the ability to differentiate in into any cell whereas ones in bone marrow can only become white blood cells, etc.

Question 24

What can Stem Cells be used for? (2 marks)

Answer 24

For the creation of new organs (e.g. Livers, Gall bladders) and for the treatment of Parkinson’s disease.

Question 25

Describe bacterial cells in one word. (1 mark)

Answer 25

Microorganisms

Question 26

Another word for Cell membrane. (1 mark)

Answer 26

Plasma Membrane

Question 27

What is the name given to enzymes that can work at a wide range of temperatures? (1 mark)

Answer 27

Thermostable