1.1 Cell structure

Question 1

Eukaryotes

what are in eukaryote cells?

Answer 1

Plant: Nucleus, cell membrane, cytoplasm, mitochondria, ribosomes, cell wall, choloroplasts, vacuole
Animal: Nucleus, cell membrane, cytoplasm, mitochondria, ribosomes

Question 2

Prokaryote

what are in prokaryote cells

Answer 2

Eg: Bacteria
cell membrane, ribosomes, cell wall, cytoplasm, plasmids, loops of DNA

smaller in size

Question 3

cell specialisation

Nerve cell

function, adaptation, parts

Answer 3

Function: send electrical impulses around the body
Adaptations:
* long axon to cover a larger distance
* myelin sheath speeds up nerve impulses

Parts: Dendrite, axon, myelin sheath,

Question 4

cell specialisation

Muscle cells

function, adaptation

Answer 4

Function: contraction for movement

Adaptation:
* layers of protein filament which can slide over each other, causing contractions
* lots of mitochondria to provide sufficient energy for contraction (via respiration)

Question 5

cell specialisation

Sperm cell

function, adaptations, parts

Answer 5

Function: reproduction
Adaptations:
* nucleus - contains chromosomes (haploid)
* acrosome has digestive enzymes that can break the outer layer of an egg cell
* mid-piece has mitochondria to release energy for the flagellum
* the flagellum rotates, allowing the sperm to move

parts: acrosome, mid-piece, flagellum

Question 6

cell specialisation

Root hair cell

function, adaptation

Answer 6

Function: absorption of water and mineral ions from the soil
Adaptations:
* root hair to increase surface area - water intake is greater
* thinner walls - water can move easier - short diffusion distance
* mitochondria - active transport of mineral ions

Question 7

cell specialisation

Xylem vessel

function, adaptations

Answer 7

Function: transport tissue for water and dissolved ions
Adaptations:
* no top and bottom walls - continuous hollow tubes - water flows upwards
* dead cells - free passage of water
* outer walls are thickened with lignin - strengthens the tubes, supports the plant

Question 8

cell specialisation

Phloem cells

function, adapation

Answer 8

Function: transport of dissolved sugars and amino acids
Adaptations:
* made of living cells and supported by companion cells
* cells are joined end-to-end and have sieve plates - allows contents to flow easily
* few subcellular structures to aid the flow of materials

Question 9

cell differentiation

What is cell differentiation like in animals?

Answer 9

most cells differentiatiate at an early stage of its development.
animals cells lose their ability to differentiate after they have become specialised early in the life.

Question 10

cell differentiation

Cell division in animals

Answer 10

cell division is mainly restricted to repair and replacement in mature animals

Question 11

cell differentiation

cell differentiation in plant cells

Answer 11

Plants have the ability to fully differentiate throughout their entire life

not only in early stages of development

Question 12

microscopy

How has microscopy developed over time?

Answer 12

over centuries, the magnification and resolution has increased to enhance visual detail.

Question 13

microscopy

Features of light microscopes

Answer 13

• uses light and lenses
• can see cells and large subcellular structures (stains are needed to highlight)

Question 14

microscopy

Features of electrons microscopes

Answer 14

• uses beams of electrons
• has a higher resolution and magnification
• able to see many more subcellular structures (eg: mitochondria)
• helped have a better understanding of structure of nucleus/cell membrane

Question 15

microscopy

Formula for magnification

Answer 15

Magnification = image size / actual size

Image size: in mm
actual size: in µm

magnification: no units