module 2 organisation of living things

Question 1

Explain the hierarchical structural organisation of organelles, cells, tissues, organs, systems, and organisms

Answer 1

Organelles -> cells -> tissues -> organs -> systems -> organisms
Specialised cells make up tissues with different types of tissues forming organs that carry out particular function within an organ.

Question 2

Explain characteristics of unicellular organisms

Answer 2

• Contain only one cell responsible for all life processes
• Simple structure
• Limits metabolic reactions
• Large surface area for all substances to diffuse across
• All prokaryotes are unicellular

Question 3

Example of a unicellular organism

Answer 3

Bacteria (salmonella)

Question 4

Explain characteristics of colonial organisms

Answer 4

• Cells that form a cooperative group (colony) but can survive on their own
• Could be classed as a single celled organism
• More efficient as a colony
•

Question 5

Example of a colonial organism

Answer 5

EXAMPLE: Blue-bottle

Question 6

Explain characteristics of multicellular organisms

Answer 6

• Made up of different types of cells
• Similar cells grouped together that communicate to perform specialised functions that combine together for efficient functioning
• Rely less on diffusion and are less efficient
• All cells have the same DNA
• Could not survive by themselves

Question 7

Example of a multicellular organism

Answer 7

Animals and Plants

Question 8

Where do specialists cells come from?

Answer 8

All specialised cells originate from cells that are known as stem cells. These stem cells are undifferentiated and are able to divide many times of a long period and become specialised. Once cells have become specialised to form a particular type of cell, they lose their capacity to develop into other types of cells.

Question 9

What is a part in the body that exchanges substances with the environment and has structural features that allow them to increase their surface area to volume ration ultimately allowing them to exchange the required materials more efficiently

Answer 9

the alveoli

Question 10

explain the role of the respiratory system

Answer 10

• Work with the cardiovascular system
• Transports oxygen to every cell and remove carbon dioxide.
• Needs air which must be taken in from the environment
• Oxygen in atmosphere transferred into the blood
• Different animals use the respiratory system differently
• Gills, tracheal system – insects

Question 11

structures in the respiratory system- the pharynx?

Answer 11

Connects the nasal cavity & mouth to the larynx. It is a pathway for both food and air.

Question 12

structures in the respiratory system- the larynx?

Answer 12

Responsible for ensuring food & air go into the proper channels.

Question 13

structures in the respiratory system- the epiglottis?

Answer 13

A flap of cartilage which prevents food entering.

Question 14

structures in the respiratory system- the trachea?

Answer 14

Called windpipe. Is very flexible & mobile.
It contains cells which remove foreign particles from the air.
Divides into two bronchi

Question 15

structures in the respiratory system- the bronchi?

Answer 15

There are two bronchi leading to each lung.

The bronchi further divide into bronchioles.

Question 16

structures in the respiratory system- the bronchioles?

Answer 16

To ensure that incoming air is supplied to each alveolus.

Question 17

structures in the respiratory system- the lungs?

Answer 17

Enclose the structures of the body responsible for gas exchange Bronchioles & alveoli.
The lungs are mainly air spaces where internal gas exchange occurs.

Question 18

structures in the respiratory system- the alveoli?

Answer 18

Alveoli are small air-filled sacs.

• Increased SA
• Thin moist membrane
• Near blood supply (capillaries

Question 19

structures in the respiratory system- the capillaries?

Answer 19

Gas exchange occurs through diffusion (concentration gradient).

Question 20

What happens when stomates are open?

Answer 20

gases are able to diffuse through them

Question 21

what are lenticels?

Answer 21

• Gas exchange pores
• Found in the woody parts of the plant e.g. trunk and branches
• Composed of clusters of loose cells in the bark layer
• Diffusion of oxygen, carbon dioxide and water vapour is relatively slow

Question 22

what are pneumatophores?

Answer 22

gas exchange aerial roots, found in mangroves because they live in muddy soil.

Question 23

explain the structure of the stomata

Answer 23

•	Tiny pores that cover epidermis 
•	Gas enters and leaves
•	Each has a pair of guard cells 
-	Open and close throughout day
-	Have chloroplast
-	Reduce water loss
•	Stomata in grooves
-	as leaf dehydrates grooves close - reduced water loss
•	Stomata at bottom of pits - reduced water loss
•	Sunken of stomata - reduced water loss

Question 24

Do unicellular organisms rely on diffusion?

Answer 24

Due to their large surface area diffusion is very efficient and have no need for transport systems.

Question 25

What are heterotrophs

Answer 25

Organisms that feed on others because they cannot provide their own energy supply

Question 26

What are autotrophs

Answer 26

Organisms that can make their own energy and do not depend on others.

Question 27

Explain the steps of obtaining nutrients and energy from food

Answer 27

1. Ingestion – intake of food (eating)
2. Digestion – breakdown of food into soluble molecules that can be easily absorbed
3. Absorption – basic units of food absorbed into the bloodstream
4. Assimilation – turning the ‘food’ into tissue
5. Egestion – elimination of wastes

Question 28

what is mechanical breakdown (digestion)

Answer 28

Chewing, churning, moving (in mouth)

Question 29

what is chemical breakdown (digestion)

Answer 29

Break down large complex molecules into simpler molecules with the help of enzymes i.e. lipase, amylase in salvia

Question 30

explain the structure of the small intestine

Answer 30

long with a large surface area (good for absorption). It has an internal surface compromised of millions of tiny folds called villi.

Question 31

explain the function of the small intestine

Answer 31

• absorbs nutrients and minerals from food like glucose, water and salts. Enzymes produced in the pancreas, small intestine, and bile from the liver and gall bladder break down food products to facilitate nutrient and water absorption.

Question 32

explain the structure of the xylem

Answer 32

Xylem vessels are long, narrow, hollow tubes containing no living material and impregnated with bands or spirals of lignin. They are joined end to end and provide a continuous pathway from the roots through the stem and to the leaves for water transport.

Question 33

what does lignin do?

Answer 33

provides strength to stop the vessels from collapsing.

Question 34

what does the tracheids do?

Answer 34

transport water and are elongated with end walls that taper to a point and also impregnated with lignin

Question 35

what is transpiration

Answer 35

Loss of water from plants by evaporation of water vapour through the stoma of plant leaves.

Question 36

explain diffusion

Answer 36

the movement of a substance from a region where it has a high concentration to a region where it has a low concentration

Question 37

aerobic respiration word equation

Answer 37

Glucose + oxygen = water + carbon dioxide + (energy) ATP

Question 38

aerobic meaning

Answer 38

using oxygen

Question 39

photosynthesis word equation

Answer 39

carbon dioxide + water —> (sunlight chlorophyll) —> glucose + oxygen

Question 40

role of photosynthesis in ecosystems

Answer 40

The form of glucose enables the conversion of radiant energy into chemical energy to provide a form of energy to sustain life in the food chain