B1

Question 1

What are eukaryotes?

Answer 1

All animals and plants, made from complex cells called eukaryotic cells

Question 2

What are prokaryotes?

Answer 2

Bacteria, simple cells called prokaryotic cells

Question 3

What is in the nucleus?

Answer 3

DNA in the form of chromosomes that controls the cell’s activities

Question 4

What is cytoplasm?

Answer 4

Gel-like substance where most chemical reactions happen

Question 5

What is the mitochondria?

Answer 5

The site of cellular respiration and contain enzymes needed for reactions

Question 6

What is the cell membrane?

Answer 6

Holds the cell together and controls what goes in and out by providing a selective barrier. Also contain receptor molecules that are used for cell communication

Question 7

What is a cell wall?

Answer 7

Made of cellulose, gives support to a plant cell (exclusively plant cells)

Question 8

What are chloroplasts?

Answer 8

It’s where photosynthesis occurs.

Question 9

What is chromosomal DNA within a prokaryotic cell?

Answer 9

It controls the cell’s activities and replication. It floats freely in the cytoplasm.

Question 10

What are plasmids within a prokaryotic cell?

Answer 10

Small loops of extra DNA that aren’t part of the chromosome. Plasmids contain genes for things such as drug resistance.

Question 11

When were light microscopes invented and what do they do?

Answer 11

In the 1590s. They let us see things like nuclei and chloroplasts.

Question 12

When were electron microscopes invented and what do they do?

Answer 12

In the 1930s. They let us see much smaller things in more detail like the internal structure of mitochondria. This has allowed us to have a much greater understanding of sub-cellular structures.

Question 13

What do transmission electron microscopes do?

Answer 13

They have a higher magnification and resolution than light microscopes but they aren’t portable. They’re expensive, and it is a complicated process to prepare specimens for use.

Question 14

What are the different parts of a microscope?

Answer 14

The eyepiece lens (looked through to see + magnify image), objective lens (magnifies image eg. x4, x10 and x40), stage, clip, handle, lamp and focusing knobs

Question 15

How do you calculate magnification?

Answer 15

Eyepiece lens magnification x Objective lens magnification OR Image Size/Real Size

Question 16

What is DNA?

Answer 16

It contains all of an organism’s genetic material - the chemical instructions it needs to grow and develop. DNA is arranged into chromosomes.

Question 17

What are chromosomes?

Answer 17

They are long molecules of coiled up DNA. The DNA is divided into short sections called genes.

Question 18

What is a double helix?

Answer 18

DNA is a double helix (a double-stranded spiral). Each of the two DNA strands is made up of lots of nucleotides joined together in a long chain. Nucleotides each contain a small molecule called a “base”. The bases are A, C, G and T. Each base forms cross links to a base on the other strand, keeping the two DNA strands tightly wound together. DNA is a polymer.

Question 19

What is complementary base pairing?

Answer 19

A always pairs up with T, and C always pairs up with G.

Question 20

What do nucleotides contain?

Answer 20

Each nucleotide has the same sugar and a phosphate group. The base on each nucleotide is the only part of the molecule that varies. The base is attached to the sugar.

Question 21

How is DNA a polymer?

Answer 21

Polymers are large, complex molecules composed of long chains of monomers joined together. DNA is a polymer made up of nucleotide monomers.

Question 22

What does DNA control?

Answer 22

Protein synthesis. A section of DNA that codes for a particular protein is called a gene. Proteins are made up of chains of amino acids - each different protein is made up of a different number and order of amino acids.

Question 23

How does protein synthesis work?

Answer 23

DNA contains the gene coding for a protein. The two DNA strands unzip around the gene and used as a template to make mRNA. Base pairing ensure it’s complementary (matches the opposite strand) - this is known as transcription. The mRNA leaves the nucleus and goes to the cytoplasm, where amino acids which match the triplet codes on the mRNA are joined together in the correct order - this is known as translation.

Question 24

What are enzymes?

Answer 24

They control cell reactions. They are produced by living things and act as biological catalysts (a substance which speeds up a reaction).

Question 25

What is a substrate?

Answer 25

It changes in a reaction with an enzyme. Every enzyme has an active site - the part where it joins on to its substrate to catalyse the reaction. Enzymes usually only work with one substrate - they have a high specificity.

Question 26

What is "lock and key"?

Answer 26

A substrate fitting with an enzyme like a key fits into a lock.

Question 27

What happens if an enzyme becomes too hot?

Answer 27

Some of the bonds holding the enzyme together break - this makes the enzyme become denatured and it loses its shit. This means that the subsrate doesn't fit the active site anymore, meaning that the enzymes can't catalyse a reaction and the reaction stops. This is IRREVERSIBLE.

Question 28

How does pH affect an enzyme?

Answer 28

If the pH is too high or low, it interferes with the bonds holding the enzyme together. This can irreversibly denature the enzyme. Enzymes mostly have an optimum pH of 7.

Question 29

How does enzyme/substrate concentration affect the rate of reaction?

Answer 29

As the enzyme/substrate concentration rises, the rate of reaction also increases. However, at a certain point, there are too many of one molecule and not enough of the other to reach with and so adding more makes no difference.

Question 30

What is respiration?

Answer 30

The process of transferring energy from the breakdown of glucose. It occurs in every cell in all living things. The energy transferred by respiration can't be used directly, so it's used to make a substance called ATP. ATP stores the energy needed for many cell processes.

Question 31

What is respiration controlled by?

Answer 31

Enzymes - the rate of respiration is affected by both temperature and pH. It's an exothermic reaction - it transfers energy to the environment.

Question 32

What is aerobic respiration?

Answer 32

Aerobic - "with oxygen" - it's what happens when lots of oxygen is available. It's the most efficient way to transfer energy from glucose. The equation for this is Glucose + Oxygen -> Carbon Dioxide + Water

Question 33

What is the chemical equation for aerobic respiration?

Answer 33

C6H12O6 + 6O2 -> 6CO2 + 6H2O

Question 34

What is anaerobic respiration?

Answer 34

Anaerobic - "without oxygen" - it's not the best way to transfer energy from glucose as it transfers much less energy per glucose molecule than aerobic.

Question 35

Why does anaerobic respiration happen?

Answer 35

When you do really vigorous exercise, your body can't supply enough oxygen to the muscles for aerobic respiration. This means that the muscles start to respire anaerobically - the glucose is only partially broken down, and lactic acid is produced. Lactic acid causes fatigue in the muscles, and after anaerobic respiration + stopping exercise you would have oxygen debt.

Question 36

What is oxygen debt?

Answer 36

You need extra oxygen to break down all the lactic acid that's built up to allow aerobic respiration to begin again.

Question 37

What is the equation for anaerobic respiration in plants?

Answer 37

Glucose -> Ethanol + Carbon Dioxide

Question 38

What are carbohydrates made up of?

Answer 38

Simple sugars - eg. glucose. These can join together in long chains, polymers, to make complex carbohydrates - eg. starch or glycogen. The polymer molecules can break down back into sugars - they are broken down by enzymes in the mouth and small intestine.

Question 39

What are proteins made up of?

Answer 39

Amino acids - they are polymers made of long chains of amino acids. Amino acids contain carbon, nitrogen, hydrogen and oxygen atoms. Proteins are broken down by enzymes in the stomach and small intestine.

Question 40

What are lipids made up of?

Answer 40

They are fats and oils made from glycerol and three fatty acids. They aren't polymers because they don't form long chains of repeating units. Lipids contain carbon, hydrogen and oxygen atoms. They are broken down by enzymes in the small intestine.

Question 41

How do you test for the different biological molecules?

Answer 41

Proteins - Biuret test (colour changes purple)

Question 42

What is photosynthesis?

Answer 42

Plants are able to make their own food (glucose) from the sun's energy through photosynthesis. It happens inside chloroplasts - they contain chlorophyll which absorb light needed for photosynthesis.

Question 43

What is the word + chemical equation for photosynthesis?

Answer 43

6CO2 + 6H2O -> C6H12O6 + 6O2

Question 44

What are the three factors which affect the rate of photosynthesis?

Answer 44

Light intensity, concentration of CO2 and temperature

Question 45

How does light affect photosynthesis?

Answer 45

Light transfers energy needed for photosynthesis. As the light level is raised, the rate of photosynthesis increases steadily - but only up to a certain point. Beyond that point, it'll be either temperature or CO2 level which is the limiting factor.

Question 46

How does CO2 affect photosynthesis?

Answer 46

CO2 is one of the raw materials needed for photosynthesis. As with light intensity the concentration of CO2 only increases the rate of photosynthesis to a certain poitn.

Question 47

How does temperature affect photosynthesis?

Answer 47

It has to be just right - if the temperature is the limiting factor, it's because it's too low - the enzymes needed for photosynthesis work more slowly at low temperatures. But if it gets too hot, the enzymes needed would denature.