Topic 1.1 Cell Intro

Question 1

Characteristics of Life

Answer 1

M- Metabolism
R- Response
H- Homeostasis
G- Growth
R- Reproduction
E- Excretion
N- Nutrition

Question 2

Cell Theory

Answer 2

1. All living things are composed of cells
2. The cell is the smallest unit of life
3. Cells only arise from pre-existing cells

Question 3

Cells that challenge the Cell Theory

Answer 3

Multi-nucleated striated muscles

Question 4

Stem cells are unspecialized cells that can:

Answer 4

• Continuously divide and replicate

- Have the capacity to differentiate into specialized cell types

Question 5

Potency

Answer 5

• Totipotent: can differentiate into any type of cell
• Pluripotent: can differentiate into many types of cells
• Multipotent: can differentiate into a few closely-related types of cells
• Unipotent: can regenerate but can only differentiate into their associated cell type

Question 6

What is and how can Stargardt’s disease be treated using stem cells?

Answer 6

Stargardt’s is a recessive genetic condition that causes photoreceptor cells to degenerate. It causes progressive, and eventually total, loss of central vision.

The treatment involves treating embryonic (totipotent) cells to divide and differentiate to become retinal cells which are then injected into the retina. Central vision then improves as a result of more functional retinal cells.

Question 7

What happens to SA:V ratio as cell size increases?

Answer 7

As the cell size increases, the SA:V ratio decreases.

Question 8

What are the benefits of a large SA:V ratio?

Answer 8

1. Shorter diffusion pathways

2. Concentration gradients are easier to generate

Question 9

Equation for magnification

Answer 9

Drawing length/ scale bar length= magnification

Question 10

Arguments for therapeutic cloning

Answer 10

• Can be used to cure serious diseases and disabilities using cell therapy
• Transplants do not require death of another human
• Transplants are less likely to be rejected as they are exact copies of the patient
• Stem cells can be taken from embryos that have stopped developing and would have died anyways
• Embryos have no nervous system so it can be argued that they don’t feel pain.

Question 11

Arguments against therapeutic cloning

Answer 11

• Involves the creation and destruction of life
• Embryonic stem cells are capable of continuous division which could cause them to develop into cancerous cells
• Extra embryos are always produced, and the extras always end up being killed
• Religious or moral objections due to the ‘playing God’ argument