Cell Biology

Question 1

What are the two different types of cells

Answer 1

Eukaryotic (animal + plant) and Prokaryotic (bacteria)

Question 2

Difference between prokaryotic and eukaryotic

Answer 2

Prokaryotic area a lot smaller
Eukaryotic have a nucleus, prokaryotic doon’t they have single circular strand of DNA that flats freely in cytoplasm.
Also have plasmids - small rings of dna
Prokaryotic don’t have chloroplasts or mitochondria

Question 3

Difference between light microscope and electron microscope

Answer 3

Electron microisopes let you see much smaller things in more detail like mitochondria and chloroplasts. They have higher magnification and higher resolution than light microscopes. Light microscope can only see large subcellular structures e.g nucleus.

Question 4

Formula for magnification

Answer 4

Magnification= image size/actual size

Question 5

How to prepare microscope slide

Answer 5

1.Add a drop of water into the middle of a clean slide
2. Cut up an onion and separate it into layers. Use tweezers to pull off some epidermal tissue from bottom of one of the layers.
3.Using tweezers place epidermal tissue into water on the slide.
4. Add drop of iodine solution (stain). Stains are used to highlight objects in a cell by adding colour to them.
5. Place cover slip on top. Try not to get any air bubbles they will obstruct your view of the specimen.

Question 6

Differentiation

Answer 6

Process by which a cell changes to become specialised for its jon

Question 7

Sperm cell

Answer 7

Specialised for reproduction
Function - transport male dna to the female dna (the egg)
Long tail and streamlined head to help it swim to egg
Lots of mitochondria in cell to provide energy needed to swim.
Carries enzymes in its head to digest egg cell membrane

Question 8

Nerve cell

Answer 8

Specialised for rapid signalling
Function- carry electrical signals from one part of body to another.
Cells are long, to cover more distance, and have branched connections to connect to other nerve cells to form a network through out the body.

Question 9

Muscle cell

Answer 9

Function - to contract quickly
Long so they have space to contract
Lots of mitochondria to generate energy needed for contraction

Question 10

Root hair cell

Answer 10

Specialised for absorbing water and minerals
Cells on surface on plants roots which stick out into long hairs into soil.
This gives plant big surface area for absorbing water and mineral ions from the soil

Question 11

Xylem

Answer 11

Specialised to transport mineral ions and water up the plant from roots and shoots
Upon formation lignin deposited causes cells to die become hollow and joined end to end to form continuous tube for water and mineral ions to move through

Question 12

Embryonic stem cells

Answer 12

Can turn into any type of cell. So can treat most illnesses.

Question 13

Adult stem cells

Answer 13

Only found in certain places e.g bone marrow
Can’t turn into any cell type only certain ones e.g blood cells
Can be used to cure disease, e.g stem cells transferred from bone marrow of healthy person to replace faulty blood cells in patient who receives them.

Question 14

Therapeutic cloning

Answer 14

Embryo can be made to have same genetic info as patient, meaning stem cells produced from it would have same genetics as patient so wouldn’t get rejected by patients body.
Risks- cells grown in lab could become contaminated with a virus which could infect patient make them sicker.

Question 15

Stem cell controversy

Answer 15

-destroying potential human life
- some thinks patients who already exist and are sufferening re more important than the rights of embryos
-could use unwanted ones from fertility clinics

Question 16

Meristems

Answer 16

Wherestem cells are found in plant
Can differentatate through plants entire life into any type of plant cell
Can be used to produce clones of whole plants quickly and cheaply.
Can be used to grown more of rare species
Used to grown crops with desired features e.g disease restant

Question 17

chromasome

Answer 17

coiled up lengths of dna molecules.
each chromosomes caries a large number of genes

Question 18

cell cycle

Answer 18

1.the cell begins to divide.
2. the DNA replicates to form two copies of each chromosome.
3. chromosomes line up i centre of the cell, one set of chromosomes pulled to each end of cell by spindle fibres.
4. cytoplasm and cell membrane divides to for two identical daughter cells.

Question 19

how do you make sure microorganism do not get contaminated

Answer 19

• Petri dish must be sterilised before use, to kill unwanted microorganisms which will affect your results.
• sterilise innoculating loopby passing it through a hot flame.
• lid of petri dish shoud be lightly taped on, to stop microorganisms from the air getting in.
• petri dish should be upside down to stop drops of condensation falling on to the agar surface.

Question 20

diffusion

Answer 20

the net movement of particles from an area of high concentration to and are of low concentration.

Question 21

How dose the concentration gradient affect diffusion

Answer 21

the bigger the concentration gradient the faster the diffusion rate.

Question 22

How dose the concentration gradient temp affect diffusion

Answer 22

the higher the temp the faster the rate of diffusion the particles have more energy so move around faster.

Question 23

How does cell membrane affect rate of diffusion?

Answer 23

the larger the surface area of the membrane he faster the rate of diffusion because more particles can pass through at once.

Question 24

osmosis

Answer 24

the movement of water molecules across a partially permeable membrane from region of high water concentration to a region of low water concentration.

Question 25

active transport

Answer 25

the movement of substances against their concentration gradient. i.e from a lower concentration to a higher one.