Key Biological Concepts

Question 1

What are eukaryotic cells?

Answer 1

Cells that have nuclei

These cells are more complex and include all plant and animal cells.

Question 2

What are prokaryotic cells?

Answer 2

Cells that do not have a nucleus

They are simple and small cell formations

Question 3

What are the 5 sub cellular structures in an animal cell?

Answer 3

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes,

Question 4

What are the 8 sub cellular structures in a plant cell?

Answer 4

Nuclear, cytoplasm, cell membrane, mitochondria, ribosomes, cell Wall, large vacuole, chloroplasts

Question 5

What are the 5 sub cellular structures in a bacteria cell and what do that bacteria exclusive ones do?

Answer 5

• chromosomal DNA = controls the cells activity and replication and floats freely in the cytoplasm
• ribosomes and cell membrane
• plasmid DNA = small loops of extra DNA that can be passes between bacteria (they hold genes for things such as sprung resistance)
• flagella = long hair like structure that rotates to move the bacteria

Question 6

What are the functions of the nucleus and cytoplasm?

Answer 6

Nucleus- contains DNA in chromosomes and controls cell activity
Cytoplasm- gel-like substance which contains enzymes and where most the chemical reactions take place

Question 7

What are the functions of the cell membrane and mitochondria?

Answer 7

Cell membrane - holds the cell together and controls what goes in and out
Mitochondria- where most of the respiration reactions take place which transfers energy for the cell to work

Question 8

What are the functions of ribosomes and the cell wall?

Answer 8

Ribosomes -where translation of genetic material happens in the synthesis of protein
Cell wall- made of cellulose to support it and stop it bursting

Question 9

What are the functions of a large vacuole and chloroplasts?

Answer 9

Vacuole - contains cell sap to maintain the cells internal pressure keeping the cell rigid
Chloroplasts - where photosynthesis occurs (contains a green substance called chlorophyll)

Question 10

What are specialised cells?

Answer 10

Cells with particular functions or structures meaning they are adapted to perform a special function

Question 11

In what ways is an egg cell adapted to its function?

Answer 11

• contains nutrients in the cytoplasm to feed the embryo
• has a haploid nucleus
• after fertilisation it’s membrane changes structure to stop any more sperm getting in making sure the offspring gets the right amount of DNA

Question 12

In what ways is the sperm cell specialised?

Answer 12

• has a long tail so it can swim to the eggs
• it has lots of mitochondria to provide energy needed to swim
• it has an acrosome at the front of the ‘head’ where is stores the enzymes needed to digest through the egg cell’s membrane
• contains a haploid cell

Question 13

In what ways are ciliated epithelial cells that line surfaces of organs specialised?

Answer 13

-some have cilia on the top of their surface to waft substances along the surface of the tissue
(E.g. in your airways, they help move mucus up the throat so it can be swallowed)

Question 14

What is resolution?

Answer 14

how well a microscope distinguishes between two points that are close together - the higher the resolution the clearer the image

Question 15

What are light microscopes and when were they invented?

Answer 15

Invented in the 1590s

They work by letting light through the specimen so we can see sub cellular structures and so we can study living cells

Question 16

What are electron microscopes and when were they invented?

Answer 16

Invented in the 1930s (use electrons rather than light)
They have a higher magnification and resolution than light microscopes so we can get a greater understanding and view of sub cellular structures and how they work - cannot be used on living cells

Question 17

What is the equation for total magnification?

Answer 17

Total magnification = eye piece lens magnification (always x10) x objective lens magnification

Question 18

What is the equation for magnification?

Answer 18

Magnification = image size / actual size (AIM)

Question 19

What are the standard form measurements for the prefixes?

Answer 19

Millimetre = x10-3m
Micrometer = x10-6m
Nanometer = x10-9m
Picometer = x10-12m

Question 20

What is an enzyme?

Answer 20

Enzymes ate proteins that act as biological catalysts and are produced by living things

Question 21

What is a catalyst?

Answer 21

A catalyst speeds up the rate of a break down or synthesis reaction without taking part in a chemical change

Question 22

What is a substrate and active site?

Answer 22

Substrate = the molecule changed in the reaction

Active site = the part where it joins on to its substrate to catalyse the reaction

Question 23

How many substrates can enzymes catalyse for?

Answer 23

Only one as they have high specificity. This is called the ‘lock and key’ mechanism

Question 24

How does temperature affect and enzyme?

Answer 24

Changing the temperature changes the rate of an enzyme catalysed reaction as some of the bonds holding the enzyme together break changing its shape and therefore active site. This enzyme is now denatured

Question 25

What is an enzyme’s optimum?

Answer 25

The conditions enzymes work best at. This could be temperature or PH (most enzymes work best at PH7)

Question 26

How can PH affect enzymes?

Answer 26

If the PH is too high or low it interferes with the enzyme’s bonds changing its shape and active site - it is now denatured.

Question 27

How can substrate concentration affect the rate of reaction of an enzyme?

Answer 27

The higher the substrate concentration the faster the reaction as it is more likely the enzyme will meet and react with the substrate molecule (this is only up to a point as eventually all the active sites are fill so a higher concentration makes no difference)

Question 28

What is the equation for rate of reaction?

Answer 28

Rate = 1000/ time

Question 29

How are carbohydrates broken down?

Answer 29

Enzymes called carbohydrase convert carbohydrates into simple sugars such as amylase breaking down into starch into maltose

Question 30

How are proteins broken down?

Answer 30

Proteases convert proteins into amino acids | All of these processes can work the other way where smaller molecules are joined together

Question 31

How are lipids broken down?

Answer 31

Lipase enzymes convert lipids into glycerol and fatty acids | This will lower the PH of the solution they’re in

Question 32

How can you test for sugars using Benedict’s Reagent?

Answer 32

- add Benedict’s Reagent (blue) to a sample and heat it in a 75° water bath - if it tests positive it will form a coloured precipitate - the higher the concentration of reducing sugars the further the colour change goes - use this to compare the reducing sugars in solution

Question 33

How do you test for starch?

Answer 33

- just add iodine to the test sample | - if starch is present the sample changes from browny-orange to blue-black and no change occurs if starch isn’t present

Question 34

How do you test for lipids using the emulsion test?

Answer 34

- shake the test substance with ethanol for one minute until it dissolves and pour the solution into water - if there are any lipid present they will precipitate out of the liquid and show up as milky emulsion (the more lipids the more noticeable)

Question 35

How do you test for protein ps using the Biuret test?

Answer 35

- add a few drops of potassium hydroxide solution to make the solution alkaline - then add some bright blue copper(II)sulphate solution - if there is not protein it should remain blue yet if protein is present it will turn purple

Question 36

What is calorimetry?

Answer 36

How food can be burnt to see how much energy it contains

Question 37

How can you test calorimetry?

Answer 37

- Take a dry food, weight it and then skewer it on a mounted needle - add a set volume if water to a boiling tube held by a clamp which will measure the energy transferred when the food is burnt - measure the temperature of the water and set fire to the food - hold the burning food under the tube until it goes out, keep doing this until it will no longer light and then measure then water temperature

Question 38

What is the equation for calorimetry?

Answer 38

- Energy in food (joules) = mass of water (g) x temperature change of water (°C) x 4.2 - energy per gram of food (j/g) = energy in food (j) / mass of food (g)

Question 39

What is diffusion?

Answer 39

The net passive movement of molecules from and area of high concentration of that molecule to and are of low concentration (Down the concentration gradient)

Question 40

Where can diffusion happen?

Answer 40

In both liquids and gases as the particles are free to move about -only small molecules such as amino acids, glucose and oxygen can diffuse through cell membranes

Question 41

What is osmosis?

Answer 41

Osmosis is the net passive movement of water molecules from an area of high concentration to an area of low concentration through a partially permeable membrane(has small holes in it) (down the concentration gradient)

Question 42

Where does osmosis happen?

Answer 42

as water molecules move randomly they pass both ways through the membrane during osmosis but as there are more water molecules in the more concentrated side so there is a steady net flow to the other region so the solute solution becomes more dilute

Question 43

What is active transport?

Answer 43

Active transport is the movement of particles across a membrane from an area of low concentration to an area of high concentration using energy transferred during respiration (against the concentration gradient)

Question 44

What are the digestive enzymes found?

Answer 44

Carbs -salivary glands, pancreas and small intestine Protein- stomach pancreas and small intestine Lipase -Pancras and small intestine

Question 45

What are the digestive enzymes found?

Answer 45

Carbs -salivary glands, pancreas and small intestine Protein- stomach pancreas and small intestine Lipase -Pancras and small intestine