Topic 1 (Cell Biology)

Question 1

All living things are made of what

Answer 1

Cells

Question 2

There are two types of cells what are they

Answer 2

Eukaryotic and prokaryotic

Question 3

What is a eukaryotic cell

Answer 3

Complex cells like animal or plant cells

Question 4

What is a prokaryotic cell

Answer 4

A small simple cell like bacteria

Question 5

What does a nucleus do

Answer 5

Contains genetic material and controls the activities of the cell

Question 6

What is a mitochondria

Answer 6

Site of aerobic respiration, which transfers energy that cell needs to work

Question 7

What is the cytoplasm

Answer 7

Gel like substance where most of the chemical reactions take place

Question 8

What is a cell membrane

Answer 8

Holds the cell together and controls what goes in and out

Question 9

What is a ribosome

Answer 9

It is the site of protein synthesis

Question 10

What is a cell wall

Answer 10

Rigid cell wall made of cellulose supports the cell and strengthens it

Question 11

What is a permanent vacuole

Answer 11

Contains cell sap (a weak solution of salts and sugars)

Question 12

What are chloroplasts

Answer 12

These are the site of photosynthesis which makes food for the plant, chloroplasts contain a green substance called chlorophyll which absorbs the light needed for photosynthesis

Question 13

Bacteria cells do not have a nucleus, what do they have instead

Answer 13

A single loose circular strand of DNA aswell as plasmids which are small circles of DNA

Question 14

What is a light microscope

Answer 14

A light microscope uses light and lenses to form an image of a specimen and magnify it.

Question 15

What is an electron microscope

Answer 15

Electron microscopes use electrons instead of light to form an image, they have a much higher magnification and much higher resolution than light microscopes

Question 16

What is magnification

Answer 16

How much bigger the image looks than the actual size

Question 17

What is resolution

Answer 17

How detailed and sharp the image is

Question 18

What is the magnification formula

Answer 18

Magnification

Image Size/
Real Size

Question 19

How do you prepare a slide

Answer 19

•Add a drop of water and clean slide
•Cut up an onion and use tweezers to pull off some epidermal tissue
•Using tweezers place epidermal tissue into water on slide
•Add a drop of iodine solution. This is a stain, stains are used to highlight objects in a cell by adding colour to them
•Place a cover slip on top

Question 20

What is differentiation

Answer 20

Differentiation is the process by which a cell changes to become more specialised

Question 21

What is an undifferentiated cell known as

Answer 21

Stem cell

Question 22

How is a sperm cell specialised

Answer 22

•Flagella and streamlined head to swim to egg
•Mitochondria to provide energy needed
•Carries enzymes to digest through egg cell membrane

Question 23

How is a nerve cell specialised

Answer 23

•Long and thin to cover more distance
•Long branched connections to connect with other nerve cells easier

Question 24

How are muscle cells specialised

Answer 24

•Long so they have space to contract
•Contain many mitochondria to generate energy for contraction

Question 25

How are root hair cells specialised

Answer 25

•Long hairs that stick out of the soil
•Large surface area to absorb water and mineral ions

Question 26

How are Xylem specialised

Answer 26

•Long thin tubes so they don’t take up a lot of space but transport water and minerals effectively
•Hollow to allow stuff to flow through it

Question 27

How are phloem specialised

Answer 27

•Long thin tubes so they don’t take up a lot of space but transport water and minerals effectively
•Very few organelles to allow stuff to flow through it

Question 28

What is the main difference between embryonic and adult stem cells

Answer 28

Whilst embryonic stem cells can specialise into any cell, adult stem cells can only differentiate into certain cells like blood cells as they are produced in the bone marrow

Question 29

How can stem cells be used to cure diseases

Answer 29

•Medicine already uses adult stem cells to cure disease e.g stem cells from a healthy persons bone marrow can replace faulty blood cells in sick people who receive them
•Embryonic stem cells could be used to replace faulty cells in sick people, you could make insulin producing cells for people with diabetes

Question 30

Why are some people against the use of stem cells

Answer 30

•Against stem cell research as they feel each embryo is a potential human life
•Embryos can not give consent to be tested on

Question 31

How can stem cells be used to create identical plants

Answer 31

•In plants stem cells are found in the meristems
•Throughout plant life cells in the meristem tissues can differentiate into any type of plant cell
•These stem cells can be used to produce clones of whole plants quickly and cheaply
•This can be used to save species from extinction or for agricultural purposes

Question 32

What are chromosomes

Answer 32

Chromosomes are coiled up lengths of DNA molecules

Question 33

There are two main stages of the cell cycle, what are they

Answer 33

•Growth and Replication
•Mitosis

Question 34

What is growth and DNA replication

Answer 34

Before a cell divides, it has to grow and increase the amount of su cellular structures such as mitochondria and ribosomes. It then duplicates its DNA so that there is one copy for each new cell. The DNA is copied and forms an X shaped chromosomes. Each ‘arm’ of the chromosome is an exact copy of the other

Question 35

What is mitosis

Answer 35

Once the cell contents have been duplicated the cell is ready for mitosis.
The chromosomes line up in the centre of the cell and the cell fibres pull them apart. Each arm going to an opposite side of the cell. Membranes form around each of the chromosomes and these become nuclei. Lastly the cytoplasm and cell membrane divides to form the two new daughter cells

Question 36

How do prokaryotic cells divide

Answer 36

Binary fission

Question 37

How do you grow bacteria

Answer 37

•Bacteria is grown in a ‘culture medium’ which contains the carbohydrates, minerals, proteins and vitamins they need to grow
•Culture medium can be a nutrient solution or agar jelly
•Bacteria grown on agar plates will form visible colonies on the surface of the jelly, or will spread out to give an even covering of bacteria
•In a school lab temperatures are kept below 25•c to reduce chances of harmful pathogens forming, in an industrial lab temperatures would be much higher so the bacteria grows quicker

Question 38

How do you keep a Petri dish uncontaminated

Answer 38

•Sterilise the Petri dish (by heating to a high temperature) before use to kill any unwanted microorganisms
•If an inoculating loop is used to transfer the bacteria,it should also be sterilised
•After transferring bacteria, the Petri dish lid should be taped on to stop pathogens getting into the agar jelly from the air
•Petri dish should be stored upside down to stop drops of condensation falling into agar jelly

Question 39

How do you test the effect of antibiotics by culturing microorganisms

Answer 39

•Place paper discs soaked in different types (or concentration) of antibiotics on an agar plate that has an even covering of bacteria
•The antibiotics should diffuse into the agar jelly. Antibiotic resistant bacteria will continue to grow around the disc but non resistant strains will die. A clear area will be left where bacteria have died called zone of inhibition
•Make sure you use a control, one paper disc with no antibiotic
•Leave plate for 48 hours at 25•c
•The more effective the antibiotic, the larger the zone of inhibition

Question 40

What is diffusion

Answer 40

Diffusion is the net movement of particles from and area of higher concentration to an area of lower concentration along the concentration gradient

Question 41

What is osmosis

Answer 41

Osmosis is the net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration

Question 42

How do root hair cells take in water

Answer 42

•The cells on a root grow into ‘hairs’
•Each branch of a root will be covered in millions of these microscopic hairs
•This gives the plant a large surface area for absorbing water and mineral ions from the soil
•The concentration is usually higher in the cell than out of it so diffusion can not take place
•Active transport allows the minerals to be absorbed from a dilute solution to a concentrated solution against the concentration gradient, it requires energy from respiration

Question 43

Where does active transport take place in humans

Answer 43

Active transport is used in the gut when there is a lower concentration of nutrients in the gut but a higher concentration in the blood

Question 44

How does gaseous exchange happen in the lungs

Answer 44

•The job of the lungs is to transfer oxygen into the blood and to remove carbon dioxide
•To do this the lungs contain millions of little air sacs called alveoli where gas exchange can take place
•As air rushes in through the bronchiole it fills the alveoli, the oxygen them diffuses into the bloodstream and the carbon dioxide diffuses out

Question 45

How are alveoli specialised to maximise diffusion

Answer 45

They have:
•Large surface area to volume ratio
•A moist lining for dissolving gases
•Walls that are one cell thick (Short diffusion distance)
•Good blood supply