1.1 - Introduction to Cells

Question 1

What are the 3 rules of cell theory?

Answer 1

• All cells come from pre-existing cells
• All living organisms are made of cells
• Cells are the smallest unit of life

Question 2

Name the 7 functions of life

Answer 2

Metabolism, reproduction, growth, homeostasis, excretion, response, nutrition

Question 3

Give an example of functions of life - for paramecium and chlorella

Answer 3

M produces enzymes which catalyse reactions in the cytoplasm
R asexually by mitosis
G food molecules digested to increase in size and dry mass
H contractile vacuoles fill with water then contract to expel water for osmoregulation
E waste products diffuse through the plasma membrane
R wave action of cilia move it differently in response to solid objects - light
N cilia waft nutrients into oral groove to form food vacuole which is digested - photosynthesis

Question 4

Define metabolism

Answer 4

The complex web of all enzyme catalysed reactions in a cell or organism

Question 5

Define reproduction

Answer 5

The production of offspring

Question 6

Define growth

Answer 6

Irreversible increase in mass/volume of an organism by cell enlargement/division

Question 7

Define homeostasis

Answer 7

Maintenance of a constant internal environment

Question 8

Define excretion

Answer 8

Removal of metabolic waste

Question 9

Define response

Answer 9

Reacting to external stimuli

Question 10

Define nutrition

Answer 10

Obtaining food to obtain organic and inorganic materials for metabolism

Question 11

What are atypical cells?

Answer 11

Larger/multinucleated exceptions

Question 12

Give 3 examples of atypical cells

Answer 12

1) skeletal muscle: average length of 30mm and consist of multi nuclei
2) aseptate fungi: composed of hyphae (multinucleated) and lade septa
3) acetabularia: 10cm in length but only one cell with one nucleus

Question 13

What is proportional to a cell’s volume and why?

Answer 13

The rate of reaction is proportional to a cell’s volume as substances must be absorbed and waste products removed

Question 14

What occurs when the SA:Vr is small?

Answer 14

• Substances enter/exit slower
• Heat transfer is slower
• This restricts cell size

Question 15

What is differentiation?

Answer 15

The development of cells in different ways to carry out specific functions.
It includes expression of certain genes in a cell’s genome and enables emergent properties.

Question 16

What are emergent properties?

Answer 16

Characteristics of an organism not evident in individual cells created by interactions.

Question 17

What are stem cells?

Answer 17

They can divide to produce more cells and can differentiate along different paths to form specialised cells by regulating gene expression.

Question 18

Where are stem cells found? (3)

Answer 18

Embryo
Umbilical cord
Bone marrow

Question 19

Embryonic stem cells (3)

Answer 19

Pluripotent
Removal kills the embryo
Not fully compatible with adult tissues

Question 20

Cord blood stem cells (5)

Answer 20

Found in umbilical cord
Multipotent
Limited number 
Easily obtained
Fully compatible with adult tissue

Question 21

Adult stem cells (5)

Answer 21

Found in bone marrow
Multipotent
Limited number
Difficult to obtain
Fully compatible with adult tissue

Question 22

Name 2 therapeutic uses of stem cells

Answer 22

Stargardt’s disease

Leukaemia

Question 23

Stargardt’s disease (3)

Answer 23

• Seen in children
• Malfunctioning of retina cells causes loss of vision
• Embryonic stem cells injected into eye where they develop attached to the retina and improve sight

Question 24

Leukaemia (3)

Answer 24

• Production of abnormally large number of WBCs
• Adult stem cells used from the patient, obtained by extracting fluid from their bones
• Then, a high dose of chemo drugs is given, killing cancer cells, before stem cells are reintroduced

Question 25

What is the equation to calculate magnification?

Answer 25

Magnification=length of image / length of real specimen