B1 Key Concepts In Biology

Question 1

How do you use a

light microscope?

Answer 1

1. Turn on the light.
2. Put the specimen on the stage.
3. Move the stage all the way up.
4. Look through the eyepiece.
5. Focus the image using the focusing knobs.

Question 2

What is

magnification?

Answer 2

how large the image is compared to the object

Question 3

What equation links

image size, actual size and magnification?

(I, A, M)

Answer 3

image size = actual size x magnification

I = A x M

I am

Question 4

Define

resolution.

Answer 4

the smallest distance between two points that can still be seen as two points

(low resolution - blurry image)

Question 5

What is the function of the

nucleus?

Answer 5

contains all the DNA

Question 6

What is the function of the

mitochondria?

Answer 6

releases energy

Question 7

What is the function of the

ribosomes?

Answer 7

makes proteins

Question 8

What is the function of the

chloroplasts?

Answer 8

to photosynthesise

Question 9

What is the function of the

cell membrane

Answer 9

control what goes in and out of the cell

Question 10

What is the function of the

cell wall?

Answer 10

strengthen the cell

Question 11

What is the function of the

vacuole?

Answer 11

provide the cell with support

Question 12

What is the function of the

cytoplasm?

(not actually and organelle)

Answer 12

provide area for most chemical reactions to occur

Question 13

What is the function of the

lysosomes?

Answer 13

break down cell parts and destroy invading viruses and bacteria

Question 14

Define

organelle.

Answer 14

structure inside a cell

Question 15

What organelles are present in a

plant cell?

Answer 15

• cell wall
• cell membrane
• chloroplasts
• nucleus
• mitchocondria
• vacuole
• ribosomes

Question 16

What plant cell organelles can be seen under

both an electron and light microscope?

Answer 16

• cell membrane
• cell wall
• vacuole
• chloroplast

electron microscope allows you to see the
- mitchocondria
- ribosomes

Question 17

What organelles are present in an

animal cell?

Answer 17

• cell membrane
• nucleus
• ribosomes
• mitchocondria

Question 18

What plant cell organelles can be seen under

both an electron and light microscope?

Answer 18

• nucleus
• cell membrane

electron microscope allows you to see
- ribosomes
- mitchocondria

Question 19

What organelles are present in

bacterial cells?

Answer 19

• flagellum
• slime coat
• cell wall
• cell membrane
• chromosonal DNA
• plasmid DNA

Question 20

What is the function of the

flagellum?

Answer 20

assists movement

Question 21

What is the function of the

slime coat?

Answer 21

protects from dehydration

Question 22

What is the function of the

chromosonal DNA?

Answer 22

stores DNA

Question 23

What is the

plasmid DNA?

Answer 23

a ring of DNA

Question 24

What are the defining characteristics of

prokaryotic cells?

(and some examples)

Answer 24

• no nucleus
• no mitchocondria or chloroplasts

(e.g. bacteria, archaea)

Question 25

# What are the defining characteristics of eukaryotic cells? | (and some examples)

Answer 25

- cells with a nucleus | (e.g. animal, plant, fungi, protist)

Question 26

What does biological mean?

Answer 26

made up of protein

Question 27

# What is a catalyst?

Answer 27

anything that speeds up reactions

Question 28

# What is catalase?

Answer 28

the **enzyme** which **catalyses** the **breakdown of hydrogen peroxide to water and oxygen**

Question 29

# Define active site.

Answer 29

the site on the enzyme where the reaction occurs

Question 30

# Define substrate.

Answer 30

the molecule the enzyme acts on

Question 31

# Define product molecule.

Answer 31

the molecule the enzyme produces

Question 32

# Describe the relationship between temperature and enzyme activity.

Answer 32

Initially, as the temperature increases, enzyme activity increases. Once the enzyme has passed its optimum temperature, enzyme activity slows down.

Question 33

# Explain the relationship between temperature and enzyme activity.

Answer 33

Initially, as the temperature increases, the enzymes have more energy so move around more. This means that they are more likely to come into contact with the enzyme. Once the enzyme has surpassed its optimum temperature, it starts to denature. Once denatured this cannot be reversed.

Question 34

# Describe the relationship between pH and enzyme activity.

Answer 34

Enzyme activity works best at its optimum pH. Anything around this is fine. However, anything too much lower or higher denatures the enzyme. This denaturing is reversible.

Question 35

# Explain the relationship between pH and enzyme activity.

Answer 35

When the pH isn't optimum for the enzyme, it denatures due to all of the protons that are being added/removed. This denaturing is reversible because the protons can just be added/removed again to reach the optimum.

Question 36

# Describe the relationship between substrate concentration and enzyme activity.

Answer 36

The higher substrate concentration, the higher enzyme activity. Enzyme activity plateaus at a certain point.

Question 37

# Explain the relationship between substrate concentration and enzyme activity.

Answer 37

The higher the substrate concentration, the more likely the substrate will react with the enzyme.

Question 38

# Define osmosis.

Answer 38

the **flow of water** across a **partially permeable membrane** from a region of **high water potential** to a region of **low water potential**

Question 39

How can you calculate the energy released from food in calorimetry?

Answer 39

energy released from food =. mass of water x temperature rise / mass of food sample

Question 40

Why do food vary in their energy content?

Answer 40

because different foods are made up of different biological molecules

Question 41

# How can you test for proteins?

Answer 41

carry out the **biuret test** **purple** is a **positive** result light **blue** is a **negative** result

Question 42

# How can you test for fats and oils? | (lipids)

Answer 42

carry out the **ethanol emulsion test** **cloudy** is a **positive** result **clear** is a **negative** result

Question 43

# How can you test for reducing sugars?

Answer 43

use **benedicts solution** **red** is a **positive** result **blue** is a **negative** result

Question 44

# How can you test for starch?

Answer 44

use **iodine solution** **blue-black** is a **positive** result **no colour change** is a **negative** result