Unit 1: AoS 2 Flashcards
Levels of organisation
- Specialised cells
- Tissues
- Organs
- Systems
- The organism
Specialised cells
- Cells with specific function
- Unique structural adaptations to carry out functions
Tissues
Groups of similar specialised cells working together to carry out a particular function
Organs
- 2 or more tissues that work together to perform specialised tasks
- Often has a distinct structure
System
- Group of organs working together
- Perform a vital task like circulating nutrients/ gases or removing waste material
Role of root hair cells
- Absorb water from the soil
- Have a branch-like structure to increase surface area and therefore increase ability to absorb
Guard cells
Specialised cells surrounding stomata which function to opan and close stomatal pores
Stomata
- 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
Xylem tissue role
Transports water and mineral ions throughout the plant (from roots to leaves)
Xylem structure
- Rigid tube structure with pits in the walls
- This allows movement of substances from neighbouring vessels
How does water move through xylem tissue
- 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
Phloem tissue structure
- Elongated cells form sieve tubes
- Perforated by holes called sieve plates
- Each sieve plate has a companion cell
Phloem tissue role
- Transports organic solutes e.g sugars produced during photosynthesis around the plant
- Moves the molecules in more than one direction (to roots and stems)
Translocation
- 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
Role of the digestive system
Breaking down and absorbing ingested food materials through manual and chemical digestion into nutrients to be absorbed and used by the body
Oesophagus role and structure
- Hollow tube connecting mouth to the stomach
- Moves food via peristalsis
Stomach role and structure
- Muscular organ that breaks down food using highly acidic gastric juices
- Then moves food using muscle actions to the small intenstine
Small intenstine role and structure
- Long, folded tube- high SA:V ratio
- Absorbs usable nutrients into bloodstream
Large intestine role
- Absorbs water and dissolved minerals (ions)
- Solid waste excreted as faeces
Salivary glands role
- Releases saliva to moisten food
- Saliva contains enzymes to begin starch breakdown
Pancreas role
- Releases enzymes into small intestine
- Secretes blood sugar absorption and regulation hormones such as insulin and glucagon
Liver role
- Takes raw materials from the intestine and metabolises them
- Including detoxification, storage and bile production
Gall bladder role
- Stores bile produced by the liver
- Releases them into small intestine to help emulsify fats
Role of excretory system
- Water regulation
- Removal of nitrogenous waste products produced by cells
Role of the kidneys
- Filter the blood
- Funnel nitrogenous wastes into bladder for excretion
Structure and function of the nephron
Refer to OneNote diagram
Cohesion
- 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
Adhesion
- 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
