B1: Cell Structure and transport and microscopy

Question 1

Describe magnification

Answer 1

Magnification is how much bigger the image you see is, than the actual specimen itself

Question 2

Describe resolution

Answer 2

Resolution is the smallest distance you can see between two separate points.

Question 3

what are the advantages of using a light microscope (3)

Answer 3

• They use a beam of light to form an image so therefore it can be used almost anywhere
• The best light microscopes can magnify things up to 2,000 times larger.
• small and cheap

Question 4

what are the disadvantages of using a light microscope

Answer 4

• cannot resolve distances smaller than 200nm (the size of a visible light wave)

Question 5

what are the advantages of using an electron microscope (3)

Answer 5

• They are used to study the inside of the cells
  -they use a beam of electrons to form an image
• They can magnify objects up to 2,000,000 times larger

Question 6

What are the disadvantages of using an electron microscope

Answer 6

• They are large and expensive
• ## They have to be kept in special rooms to control the temperature, pressure and humidity

Question 7

magnification formula

Answer 7

magnification = size of image/size of real object

Question 8

Cell membrane function

Answer 8

Controls what goes in and out of the cell

Question 9

Nucleus function

Answer 9

Contains the cell’s genetic material (DNA) which controls the cells activity

Question 10

Mitochondria function

Answer 10

powerhouse of the cell, where aerobic respiration occurs, releasing energy

Question 11

Cytoplasm function

Answer 11

where chemical reactions happen, contains enzymes

Question 12

Ribosome function

Answer 12

Makes proteins

Question 13

Vacuole function

Answer 13

stores food, nutrients and waste products

Question 14

Cell wall function

Answer 14

provides strength and structure, protects the the cell

Question 15

Chloroplast function

Answer 15

Where photosynthesis takes place

Question 16

Large central vacuole function

Answer 16

stores water, pigment and toxic materials

Question 17

what are the differences between an animal cell and a plant cell (4)

Answer 17

• Plant cells have cell walls, animal cells only have a cell membrane
• Plant cells contain chloroplast, animals cells don’t
• Plant cells have vacuoles, animals cells don’t
• plants cells have a rectangular shape while animal cells have a circular shape

Question 18

Compare prokaryotic cells and eukaryotic cells

Answer 18

• Prokaryotic cells don’t have a true nucleus;
  eukaryotic cells do
• Prokaryotic cells lack membrane-bound
  organelles; eukaryotic cells have them
• Prokaryotic cells are smaller; eukaryotic
  cells are larger
• Prokaryotic cells are simpler; eukaryotic
  cells are more complex

Question 19

Genetic material (prokaryotic cell)

Answer 19

Contains DNA

Question 20

Plasmids (prokaryotic cell)

Answer 20

Replicate and move between cells so that genetic information can be shared.

Question 21

Flagella (prokaryotic cell)

Answer 21

Rotate or move in a whip-like motion to move the bacterium.

Question 22

Pilli (prokaryotic)

Answer 22

Adherence to surfaces, which facilitates infection, and is a key virulence characteristic

Question 23

Why do animals have specialised cells?

Answer 23

To carry out a particular role in the body

Question 24

Red blood cell function

Answer 24

To carry oxygen around the body

Question 25

Nerve cell function

Answer 25

Help contraction of muscles or the relaxation of muscles

Question 26

Prokaryotic cells

Answer 26

Bacteria cells
Do NOT have nucleus or mitochondria

Question 27

Eukaryotic cells

Answer 27

Plant and animal cells (and fungi) are all eukaryotic cells, they have a nucleus (and other organelles e.g. mitochondria)

Question 28

Compare the structure of a specialised and generalised animal cell

Answer 28

• Generalised cells have a simple structure
  and can perform basic functions.
• Specialised cells have a more complex
  structure and are adapted to perform
  specific functions within the body.

Question 29

How are blood cells adapted

Answer 29

• contains haemoglobin (red pigment which binds to oxygen
• biconcave disks fro increased surface area for diffusion
• No nucleus for more space for haemoglobin

Question 30

What is the percentage composition of the red blood cell

Answer 30

40-45%

Question 31

how are sperm cells adapted

Answer 31

• A tail to move them towards an egg cell.
• Many mitochondria to provide energy.
• nucleus carries half the amount of genetic material as a normal adult cell

Question 32

Define specialised cells

Answer 32

Cells which have a key role in the body/plant by having a specific cell/structure

Question 33

Define differentiation

Answer 33

The process by which a cell changes to become specialised

Question 34

Describe diffusion

Answer 34

The net movement of particles from an area of higher concentration to an area of low concentration

Question 35

Define osmosis

Answer 35

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

Question 36

Area to volume ration

Answer 36

As the organism gets larger
Surface area : volume ration decreases