What is the structure of phloem tubes and what do they do?
- made of columns of elongated living cells with small pores in the end walls to allow cell sap to move through
- they transport food substances in both directions ( made in the leaves ) to the rest of the plant for immediate use or for storage - this process is called translocation
What is the structure of xylem tubes and what do they do?
- made of dead cells joined end to end with no end walls between them and a hole down the middle - strengthened with lignin
- they carry water and mineral ions from the roots to the stem and leaves- this is called the transpiration stream
What is the definition of transpiration?
The process in which water evaporates from the leaves resulting in more water being drawn up from the roots
What are the 4 factors affecting transpiration?
- temperature as water evaporates faster in higher temperatures
- humidity as the drier the air the steeper the concentration gradient of water molecules
- wind speed as wind removes water vapour - maintaining a steeper concentration gradient
-light intensity as the stomata opens wider to let more carbion dioxide into the leaf for photosynthesis
What is the order of organisation in organisms and breifly describe each one?
Cells- small basic structures made up of organelles that are adapted to perform specific functions
Tissues- a group of similar cells that work together to perform a similar function
Organs- a group of different tissues working together to perform a similar function
Organ systems- a group of organs working together to perform a specific fuction
Organisms- a living thing whose organ systems keep the organism alive and healthy
What is the function of the mouth in the digestive system?
- have teeth that physically digest food by chewing to increase the surface area
- have salivary glands that release saliva that moistens food and chemically digests it by containing amylase that break down sugar into starch
What does bile do? Where is it stored and produced?
- neutralises stomach acid and emulsifies fats to increase surface area of food to help digestion
- made in the liver
- stored in the gall bladder
What is the function of the liver in the digestive system?
Makes bi
What is the function of the liver in the digestive system?
Releases amylase (sugar into starch), protease (proteins into amino acids) and lipase ( lipids into fatty acids and glycerol) for chemical digestion
What is the function of the small intestine and how is it adapted?
- where nutrients diffuse into the blood
- Contains amylase , protease and lipeasefor chemical digestion
- has villi and micro villi that are only one cell thick and have lots of blood vessels in order to increase surface area to speed up diffusion
What is the function of the oesophagus in the digestive system and how is it adapted?
- lined with muscles to help complete peristalsis (rhythmic motion that helps moves food from the mouth into the stomach)
What is the function of the stomach in the digestive system?
- churns food to increase surface area ( mechanical digestion)
- contains protease,
- has hydrochloric acid that provides a low ph for the protease and kills bacteria ( but does not break down food)
Where is waste stored and excreted?
Stored - rectum
Excreted - anus
What is the function of the large intestine ?
To reabsorb water
What is the function of the waxy cuticles in a leaf?
Helps to reduce water loss
What is the function of the spongy mesophyll tissue in a leaf?
It allows gas exchange by having an irregular structure
What is the function of the stomata in a leaf ?
Let’s carbon dioxide diffuse directly into the leaf
What is the function of guard cells in a leaf?
Open and close the stomata
What is the function of the stomata in a leaf ?
Allows carbon dioxide to diffuse directly into the leaf
What is the function of guard cells in a leaf?
Open and close the stomata
How is the epidermal tissue in a leaf adapted and what is its function?
- covered in waxy cuticles and is transparent
- allows sunlight to reach the palisade layer
What does the palisade mesophyll tissue contain lots of and why?
Lots of chloroplasts for photosynthesis
What are the 4 main things that make up blood?
- red blood cells - carry oxygen
- platelets - small fragments of cells with no nucleus that help blood clot
- plasma - pale liquid that carries everything
(E.g glucose, hormones, proteins) - white blood cells - defend against infection
What do arteries do and how are they adapted ?
Carry oxygenated blood at high pressure away from the heart
- have thick muscular walls and connective tissue to provide strength
- have a narrow lumen
