The Cell Theory and Level of Organisaiton

Question 1

The Cell Theory

Answer 1

• All living organisms are composed of cells, they may be unicellular or multicellular
• The cell is the basic unit of life
• Cells arise from pre-existing cells

Question 2

The modern version of cell theory

Answer 2

• Energy flow occurs within cells
• Heredity information (DNA) is passed on form cell to cell
• All cells have the same basic chemical composition

Question 3

Examples of Unicellular Eukaryotes

Answer 3

• Amoeba
• Paramecium
• Euglena

Question 4

Stem Cells

Answer 4

A stem cell is an unspecialised cell which has the ability to differentiate into any cell

Question 5

Levels of organisation

Answer 5

Multicellular organisms’ cells are specialised according to the functions they perform leading to division of labour

Question 6

Tissue

Answer 6

An aggregation of similar cells carrying out the same function is a tissue e.g. muscle blood.

Question 7

Epithelial tissue

Answer 7

Epithelial tissue covers internal and external surfaces. It has a protective or secretory function.
These are different types:

Question 8

Cuboidal epithelial

Answer 8

• Cube shape
• 1 cell thick
• Found in Kidney tubule, kidney, liver, ureter, ovary, glands

Question 9

Ciliated epithelial

Answer 9

• They have cilia (small hairs) that beat
• They move substances eg mucus in trachea
• Found in trachea/bronchi/bronchioles/oviduct/fallopian tube

Question 10

Squamous epithelial

Answer 10

• Flattened cells on a basement membrane
• 1 cell thick so provides short diffusion pathway
• Found in walls of alveoli (lungs) and Bowman’s capsule of nephron in the kidney

Question 11

Muscle tissue

Answer 11

Function - contract causing movement
3 types:
-Skeletal muscle
-Smooth muscle
-Cardiac muscle

Question 12

Skeletal Muscle - Striated (striped)

Answer 12

• Attached to bone
• Function - contraction causes locomotion (movement) in animals
• Voluntary muscles - you decide to move them

Question 13

Smooth Muscle - Unstriated (No stripes)

Answer 13

• Involuntary muscles - don’t decide to move them
• Causes substances to move along tracts eg food
• Found in digestive tract, respiratory tract, walls if blood vessels and skin

Question 14

Cardiac Muscle - Striated (striped)

Answer 14

• Involuntary muscles
• Only found in heart
• Causes the heart beat - pumps blood
• Never stops working

Question 15

Connective tissue

Answer 15

• Function - connects, supports or separates tissues and organs
• Contains elastic and collagen (protein) fibres in an extracellular fluid or matrix
• Between fibres are fat storing cells and white blood cells

Question 16

Organ

Answer 16

• An organ is an aggregation of several different tissues to carry out a particular function for the whole organism
• Eg skin, heart, leaf

Question 17

Organ system

Answer 17

A group of organs working together to carry out a major job

Question 18

Organism

Answer 18

All the organ systems working together making an organism