Book 1- cells

Question 1

What is a cell?

Answer 1

the basic unit of living organisms

Question 2

What is a tissue?

Answer 2

a smaller group of similar cells, which carry out a specific function

Question 3

What is an organ?

Answer 3

a group of different tissues

Question 4

What does unicellular mean?

Answer 4

its made up of 1 cell only

Question 5

How are eukaryotes characterised?

Answer 5

by the presence of a nucleus and other cell organisms

Question 6

What do plant cells have that animal cells don’t?

Answer 6

1. ) a cellulose wall providing support and shape
2. ) starch grains present in the cytoplasm
3. ) chloroplasts containing chlorophyll
4. ) vacuole containing sugars, salts and sometimes pigment

Question 7

What are plasmadesmata?

Answer 7

channels for exchanging substances between adjacent plant cells

Question 8

What do prokaryotes contain?

Answer 8

DNA, cell membrane, ribosomes, cytoplasms

Question 9

what structures may a prokaryote be?

Answer 9

capsule, plasmid, flagella

Question 10

explain virsues

Answer 10

they are accelular. they are not alive by themselves, therefore must enter the human and take over a cell to multiply. consists of DNA or RNA, capsid, lipid envelope and attachment protein

Question 11

The function of the nucleus?

Answer 11

contains DNA, which codes for proteins

Question 12

The function of chloroplast?

Answer 12

carries out photosynthesis, producing glucose

Question 13

The function of the mitochondria?

Answer 13

carries out aerobic respiration, which releases energy

Question 14

The function of ribosomes?

Answer 14

Carries out protein synthesis by joining amino acids together

Question 15

The function of SER

Answer 15

produces fats and transports them around the cell

Question 16

The function of RER

Answer 16

has ribosomes attached, which makes proteins. transports proteins to the Golgi body

Question 17

The function of Golgi body?

Answer 17

modifies and packages proteins, produces vesicles and lysosomes

Question 18

The function of lysosomes?

Answer 18

digest unwanted materials, such as bacteria

Question 19

Why do muscle cells contain many mitochondria?

Answer 19

mitochondria respire, more means more respiration, more energy released for muscle contraction

Question 20

Where are epithelial cells found?

Answer 20

lining the inside or outside of organs

Question 21

How are epithelial cells suited to its purpose?

Answer 21

1. )folded into microvilli providing a large SA for diffusion.
2. ) lots of microvilli meaning higher rate of respiration providing more ATP for the active uptake of digested foods.

Question 22

How is a palisade mesophyll cell adapted to photosynthesis?

Answer 22

1. ) possess numerous chloroplasts
2. ) have thin cell walls providing a short diffusion pathway
3. ) columnar providing a large SA
4. )vertically arranged so there are fewer cell walls for light to pass through

Question 23

What is differential Centrifugation?

Answer 23

a technique that is used to separate organelles according to their density.

Question 24

Explain Centrifugation (6)

Answer 24

1.) The cells are broken by homogenising a tissue in an ice cold, isotonic, buffer solution using a blender.
Ice cold- prevents enzyme action that might cause digestion of the organelles,
Isotonic- allows water to move in and out of organelles equally preventing organelles bursting.
Buffer solution- maintains the PH so that proteins aren’t denatured.
2.) the homogenate us then filtered to remove debris and any remaining whole cells.
3.) homogenate is poured into a tube and spun in a centrifuge at a low speed, causing the heaviest organelle to form a sediment at the bottom.
4.) the supernatant contains lighter organelles. it is poured into another tube and spin for longer at a higher speed

Question 25

What order do organelles separate in in centrifugation?

Answer 25

nuclei, chloroplasts, mitochondria, ER, ribosomes

Question 26

Magnification equation??

Answer 26

size of image/ size of real image

Question 27

What is the resolution?

Answer 27

how detailed the image is

Question 28

2 types of electron microscopes?

Answer 28

transmission electron and scanning electron microscope

Question 29

How does TEM work?

Answer 29

uses electromagnets to focus a beam of electrons through a thin specimen and then focusing the electrons to form an image on the screen.

Question 30

how does SEm work?

Answer 30

scans a beam of electron onto a specimen which collects the electrons scattered by the surface

Question 31

Advantages and disadvantages of SEM

Answer 31

A- 3D, can be used on thick specimens

D- gives lower resolution images, can only be used on dead specimens due to the vacuum

Question 32

Advantages and disadvantages of TEM

Answer 32

A- high resolution images

D- can only be used on think specimens, can only be used on dead specimens due to the vacuum

Question 33

Why is electron microscopy better than light?

Answer 33

• electrons have a shorter wavelength, providing a better resolution.
• a higher magnifications images blurs using light due to poor resolution

Question 34

How’s a microscope slide prepared?

Answer 34

1. ) pipette a small drop of water onto the centre of the slide
2. ) use twezers to place a thin specimen on top if the water drop
3. )add a drop of a stain to highlight the object.
4. ) add the cover slip. standing it upright and lowering to avoid bubbles