From Big to Small

Question 1

What are organelles?

Answer 1

Small structures inside a cell’s cytoplasm which carry out functions (jobs) to keep the cell alive .

Question 2

What is the function of the nucleus?

Answer 2

1. Controls the activity of the cell by making proteins
2. Contains chromosomes - strands of DNA which carry genes (each gene codes for a protein)

Question 3

What is the function of ribosomes?

Answer 3

Synthesises (assembles) proteins from amino acids

Question 4

What is the function of the vacuole?

Answer 4

Filled with a watery liquid called cell sap; stores dissolved sugars, mineral ions and other substances.

Question 5

How do microscopes work?

Answer 5

Light is reflected off structures inside the sample (object on the slide). The lenses focus that light so that we ca see the object.

Question 6

What does changing the objective lens on a microscope do?

Answer 6

By changing the objective lens, we change the magnification (how many times bigger the object is than in real life)

Question 7

What are cells?

Answer 7

The smallest functional unit of life and contain a number of organelles (e.g nucleus). The cells in an organism are not all the same, there are many different types, each with a different job. Different types of cells are described as specialised.

Question 8

What are tissues?

Answer 8

A group of similar cells which work together to carry out the same function (job). An example in humans is muscle tissue.

Question 9

What are organs?

Answer 9

Organs are made up of several different tissues working together to carry out a more complex function. In humans, muscle is one of the tissues making up the heart.

Question 10

What are organ systems?

Answer 10

Organ systems are made up of several different organs working together to carry out a complex function essential to life e.g. circulating blood around the body).

Question 11

What do all cells begin as?

Answer 11

Stem cells - these are not specialised to a particular job, but are able to divide over and over to make new cells.

Question 12

What is used to test for sugars?

Answer 12

Benedict’s solution

Question 13

How do you conduct a test for sugars?

Answer 13

1. Add benedict’s solution to a sample of food
2. Place in a water bath at 80°c for 5 minutes
3. If sugar is present, the colour will change from blue to a brick red. If it turns green, yellow or orange, sugar is present but in a lower concentration

Question 14

What is used to test for starch?

Answer 14

Iodine solution

Question 15

How do you conduct a test for starch?

Answer 15

1. Add a few drops of orange iodine solution to the sample on a spotting tile.
2. If starch is present, the solution will turn into a blue-black colour

Question 16

How do you conduct a test for protein?

Answer 16

1. Add 2cm³ water to a food sample and shake (if not already liquid)
2. Add an equal volume of dilute potassium hydroxide and shake
3. Add 2 drops of 1% copper sulfate solution
4. If protein is present the colour will change to a pale purple

Question 17

What is used to test for protein?

Answer 17

Biuret

Question 18

What is used to test for lipids?

Answer 18

1. The food sample is placed in a test tube
2. Add a small volume of absolute ethanol and shake to dissolve any lipid in the alcohol.
3. Add an equal volume of water
4. A cloudy white colour (Caused by emulsion forming) indicates the presence of lipids.

Question 19

What is the function of the cell membrane?

Answer 19

Boundary between the cytoplasm and the cell’s surroundings. Controls what substances leave and enter the cell (selectively permeable)

Question 20

What is the function of the Cytoplasm?

Answer 20

Jelly like liquid where chemical reactions occur.

Question 21

What is the function of the mitochondria?

Answer 21

Carries out some reactions of aerobic respiration, producing ATP (energy carrier molecule)

Question 22

What is the function of the chloroplast?

Answer 22

Absorb light energy and use it to carry out the reactions of photosynthesis, making biological molecules for plant cells

Question 23

What is the function of the cell wall?

Answer 23

Made of cellulose (a carbohydrate) in plants. Helps to keep plants in a fixed shape (and so keeps the plant upright)