Unit 1: AoS 2

Question 1

Levels of organisation

Answer 1

1. Specialised cells
2. Tissues
3. Organs
4. Systems
5. The organism

Question 2

Specialised cells

Answer 2

• Cells with specific function
• Unique structural adaptations to carry out functions

Question 3

Tissues

Answer 3

Groups of similar specialised cells working together to carry out a particular function

Question 4

Organs

Answer 4

• 2 or more tissues that work together to perform specialised tasks
• Often has a distinct structure

Question 5

System

Answer 5

• Group of organs working together
• Perform a vital task like circulating nutrients/ gases or removing waste material

Question 6

Role of root hair cells

Answer 6

• Absorb water from the soil
• Have a branch-like structure to increase surface area and therefore increase ability to absorb

Question 7

Guard cells

Answer 7

Specialised cells surrounding stomata which function to opan and close stomatal pores

Question 8

Stomata

Answer 8

• Openings or pores in plant tissue that allow water vapour and oxygen out of the leaf and co2 into the leaf
• Typically on plant leaves but can be on stems

Question 9

Xylem tissue role

Answer 9

Transports water and mineral ions throughout the plant (from roots to leaves)

Question 10

Xylem structure

Answer 10

• Rigid tube structure with pits in the walls
• This allows movement of substances from neighbouring vessels

Question 11

How does water move through xylem tissue

Answer 11

• From the roots into the xylem tissue
• Moves through the xylem tissue through a mechanism called transpiration
• The negative pressure created by the evaporation of water vapour through the stomata pulls water up the xylem through adhesion and cohesion

Question 12

Phloem tissue structure

Answer 12

• Elongated cells form sieve tubes
• Perforated by holes called sieve plates
• Each sieve plate has a companion cell

Question 13

Phloem tissue role

Answer 13

• Transports organic solutes e.g sugars produced during photosynthesis around the plant
• Moves the molecules in more than one direction (to roots and stems)

Question 14

Translocation

Answer 14

• Active transport of sugars from the leaves to other tissues
• Pumped into companion cell at the source (leaves) and then moves into the sieve tube
• Travels up or down to sink cells through the phloem

Question 15

Role of the digestive system

Answer 15

Breaking down and absorbing ingested food materials through manual and chemical digestion into nutrients to be absorbed and used by the body

Question 16

Oesophagus role and structure

Answer 16

• Hollow tube connecting mouth to the stomach
• Moves food via peristalsis

Question 17

Stomach role and structure

Answer 17

• Muscular organ that breaks down food using highly acidic gastric juices
• Then moves food using muscle actions to the small intenstine

Question 18

Small intenstine role and structure

Answer 18

• Long, folded tube- high SA:V ratio
• Absorbs usable nutrients into bloodstream

Question 19

Large intestine role

Answer 19

• Absorbs water and dissolved minerals (ions)
• Solid waste excreted as faeces

Question 20

Salivary glands role

Answer 20

• Releases saliva to moisten food
• Saliva contains enzymes to begin starch breakdown

Question 21

Pancreas role

Answer 21

• Releases enzymes into small intestine
• Secretes blood sugar absorption and regulation hormones such as insulin and glucagon

Question 22

Liver role

Answer 22

• Takes raw materials from the intestine and metabolises them
• Including detoxification, storage and bile production

Question 23

Gall bladder role

Answer 23

• Stores bile produced by the liver
• Releases them into small intestine to help emulsify fats

Question 24

Role of excretory system

Answer 24

• Water regulation
• Removal of nitrogenous waste products produced by cells

Question 25

Role of the kidneys

Answer 25

• Filter the blood
• Funnel nitrogenous wastes into bladder for excretion

Question 26

Structure and function of the nephron

Answer 26

Refer to OneNote diagram

Question 27

Cohesion

Answer 27

• Cohesion is the force of attraction between two particles of the same substance (e.g. between two water molecules)
• Water molecules are polar and can form a type of intermolecular association called a hydrogen bond
• This cohesive property causes water molecules to be dragged up the xylem towards the leaves in a continuous stream

Question 28

Adhesion

Answer 28

• Adhesion is the force of attraction between two particles of different substances (e.g. water molecule and xylem wall)
• The xylem wall is also polar and hence can form intermolecular associations with water molecules
• As water molecules move up the xylem via capillary action, they pull inward on the xylem walls to generate further tension