Unit 1 (2A): Cells as the basis of life

Question 1

What criteria must something fulfil to be classified as living? (Hint: MRS GREEN acronym)

Answer 1

M - Movement
R - Respiration (Extracting energy from carbs/fats/proteins via cellular respiration)
S - Sentsitivity (ability to react to stimuli)

G - Growth
R - Reproductive ability
E - Equilibrium (ability to maintain stable internal environment - also known as homeostasis)
E - Excretion (producing excretory waste - urine/dead cells - something that must be removed)
N - Nutrition (Extracting nutrients from surrounding environment)

Question 2

What is homeostasis/maintaining equilibrium and what is a stimuli?

Answer 2

Homeostasis: the maintenance of a stable internal environment through the adaption to external environmental change (a stimuli).

Stimuli: a detectable change in the internal or external environment of a n organism

Question 3

What are the three components of cell theory?

Answer 3

1. All living things are made up of cells
2. Cells are the smallest and most basic unit of life
3. All cells must come from pre-existing cells

Question 4

Cells can be composed differently. What organelles are prokaryotic cells composed of?

Answer 4

Plasma membrane, cytosol, ribosomes, DNA.

It is important to note that prokaryotes do not have a nucleus, contain only a single loop of circular DNA and DNA units called plasmids. They are typically smaller than eukaryotes.