Cell Structure (1.1) (M)

Question 1

What type of cells are plant and animal cells?

Answer 1

Eukaryotic cells

Question 2

What type of cell is a bacterial cell?

Answer 2

Prokaryotic

Question 3

What is the size difference between eukaryotic and prokaryotic cells?

Answer 3

prokaryotic cells are much smaller in comparison

Question 4

What is the difference in cell structure between eukaryotic and prokaryotic cells?

Answer 4

Eukaryotic: have a cell membrane, cytoplasm and genetic material enclosed in a nucleus

Prokaryotic: have cytoplasm, a cell membrane surrounded by a cell wall. The genetic material is not enclosed in a nucleus. It is a single DNA loop and there may be one or more small rings of DNA called plasmids.

Question 5

What are the sub-cellular structures of animal and plant cells?

Answer 5

• nucleus (both)
• cytoplasm (both)
• cell membrane (both)
• mitochondria (both)
• ribosomes (both)
• chloroplasts (plant only)
• permanent vacuole filled with cell sap (plant only)
• cell wall

Question 6

What is the function of the cell membrane?

Answer 6

Controls the movement of substances into and out of the cell

Question 7

What is the function of the cytoplasm?

Answer 7

Jelly-like substance, where chemical reactions happen

Question 8

What is the function of the nucleus?

Answer 8

Carries genetic information and controls activities of the cell

Question 9

What is the function of the mitochondria?

Answer 9

Where most respiration reactions happen

Question 10

What is the function of the ribosome?

Answer 10

Where protein synthesis occurs

Question 11

What is the function of the permanent vacuole?

Answer 11

Contains a liquid called cell sap, which keeps the cell firm

Question 12

What is the function of the chloroplasts?

Answer 12

Structures which contain the green pigment chlorophyll; the site of photosynthesis

Question 13

What is the function of the cell wall?

Answer 13

made of cellulose, which strengthens the cell

Question 14

How are sperm cells adapted to their function? (4 points)

Answer 14

• has a flagellum for locomotion to swim towards the egg
• middle section full of mitchondria, which transfer the energy needed for the flagellum to work
• acrosome stores digestive enzymes for breaking down the outer layers of the egg
• only has 23 chromosomes in nucleus so chromosome number doesn’t double at fertilisation

Question 15

How are muscle cells adapted to their function? (3 points)

Answer 15

• contain special proteins that slide over eachother making fibres contract
• contain many mitochondria to transfer energy needed for chemical reactions that take place as the cells contract and relax
• can store glycogen, a chemical that can be broken down and used in cellular respiration by the mitochondria to transfer energy needed for fibres to contract

Question 16

How are nerve cells adapted to their function? (4 points)

Answer 16

• myelin sheath for insulation
• lots of dendrites to make connections to other nerve cells
• an axon that carries the nerve impulse along it - it is very long which allows for quicker communication
• synapses/nerve endings are gaps between nerve cells or neurone, neurotransmitters are released and diffuse across the gap and bind to receptors which stimulate an electrical impulse

Question 17

How are root hair cells adapted to their function? (4 points)

Answer 17

• greatly increase surface area with root hair so more water can move into the cell via osmosis
• have a large permanent vacuole that speeds up osmosis from soil to cell (as more water can be stored)
• have many mitochondria that transfer energy needed for the active transport of mineral ions into the root hair cells
• don’t have chloroplasts as they are underground and light won’t reach them, so more space for other subcellular structures

Question 18

What happens as an organism develops (in terms of differentiation)?

Answer 18

As an organism develops, cells differentiate to form different types of cells.

Question 19

When do most animal cells differentiate?

Answer 19

At an early stage

Question 20

When can most plant cells differentiate?

Answer 20

They retain the ability to differentiate throughout life.

Question 21

in mature animals, differentiation is restricted to…

Answer 21

Repair and replacement

Question 22

What happens as a cell differentiates (in terms of importance)?

Answer 22

it acquires different sub-cellular structures to enable it to carry out a certain function.

Important for multi-cellular organisms

Question 23

What do we call it when a cell has fully differentiated?

Answer 23

It has become a specialised cell.

Question 24

Why have microscopy techniques improved over time?

Answer 24

Improving technology

Question 25

Why are electron microscopes useful?

Answer 25

They can produce images of higher magnification and higher resolution than light microscopes Therefore smaller subcellular structures (e.g. ribosomes, mitochondria) can be seen under an electron microscope (but not a light microscope), which has led to a **greater understanding** of subcellular structures.

Question 26

What is magnification?

Answer 26

how much bigger an object appears compared to its actual size

Question 27

What is resolution (resolving power)?

Answer 27

how well you can distinguish between objects close together (how detailed the image is)

Question 28

What is the formula for magnification?

Answer 28

magnification = image size / actual size

Question 29

What is binary fission?

Answer 29

Bacteria multiply by simple cell division

Question 30

How often can binary fission occur?

Answer 30

as often as once every 20 minutes if they have enough nutrients and a suitable temperature

Question 31

What formula do we use to determine the number of bacteria in a population after a certain time if given the mean division time?

Answer 31

2ⁿ, where n = total time / mean division time

Question 32

Where are two places bacteria can be artificially grown?

Answer 32

* a nutrient broth solution * as colonies on an agar gel plate

Question 33

What is required for investigating the action of disinfectants and antibiotics?

Answer 33

uncontaminated cultures of microorganisms

Question 34

Describe how to prepare an uncontaminated culture using aseptic technique

Answer 34

**_Pre-inoculation_** * Petri dish and agar sterilised before use to kill unwanted bacteria * inoculating loop passed through flame / sterile swab to sterilise/kill (other) bacteria **_Inoculation_** * loop/swab used to spread/streak bacterium onto agar * lid of Petri dish opened as little as possible * to prevent microbes from air entering (or microbes leaving) **_Post-inoculation_** * sealed with adhesive tape (to prevent unwanted microorganisms from air entering, but not fully as anaerobic conditions encourage pathogen growth) and stored upside down (to prevent condensation falling onto culture medium * incubate at 25^oC to allow growth of bacteria, but this is below optimum conditions (for safety)

Question 35

How would you determine which antibiotic is best to use? How would you measure it?

Answer 35

Measure zone of inhibition (cross-sectional area were no bacteria is growing). πr2

Question 36

After inoculation, why are there areas where no bacteria are growing?

Answer 36

Bacteria have been killed

Question 37

Why might an antibiotic with the largest zone of inhibition not necessarily mean that it's the best one to use?

Answer 37

It may be harmful to people *Student may need to investigate this (toxicity)*

Question 38

What does a labelled animal and plant cell look like?

Answer 38

Question 39

Do prokaryotic and eukaryotic cells have mitochondria and ribosomes?

Answer 39

Eukaryotic - both prokaryotic - only ribosomes, no mitochondria

Question 40

What are the key features of a biological drawing?

Answer 40

* Title * Magnification * Draw what is observed in the full field of view (if it asks for this, it may ask for one cell) * Draw only the sub-cellular structures that are visible * Labels of sub-cellar structures (*cell wall for plant cell rather than cell membrane*) * No shading/arrow heads/need straight lines * Draw what can be seen rather than a standard animal/plant cell diagram

Question 41

Label a microscope

Answer 41

* coarse adjustment - moves stage up and down* * fine adjustment - brings image into focus*

Question 42

Name on type of cell that does not have mitochondria and explain why?

Answer 42

Prokaryotic/bacterial cell Mitochondria is larger than prokaryotic cell *(so aerobic respiration occurs in cell membrane)*