Topic 10 Flashcards
How does absorption of water occur in plants
Root hair cell has lower water potential than surrounding soil, water moves in via osmosis.
Water moves from cell to cell due to a water potential gradient until it reaches the cell surrounding root xylem vessels
Cells surrounding xylem pump ions into it via active transport, lowering water potential of xylem
Water from surrounding cells move into xylem via osmosis
How does absorption of mineral salts occur in plants
when concentration of ions in surrounding soil is higher than root hair cell, ions diffuse into root hair cell
When concentration of ions in root hair cell is higher than surrounding soil, ions move into root hair cell via active transport
What is the function of the cambium
The cambium divides and differentiates to form new xylem and phloem tissues, thickening the stem
What is the function of the xylem
Transport water and mineral salts from root hair cells to the leaves
Provide mechanical support for the plant
What is the special characteristics of the xylem
Made of dead cells fused to form a long hollow tube
Walls are lignified to prevent collapse
No cross walls in lumen to enable water to move easily
What is the function of the phloem
Transport sucrose and amino acids from leaves to other parts of the plant
What are the special characteristics of the phloem
Consists of sieve tubes and companion cells
Sieve tubes:
- lack nuclei
- have thin layers of cytoplasm
- join to form a column with sieve plates in between
Companion Cells:
- have numerous mitochondria that release energy for transfer of sugars into phloem sieve tubes
What type of blood do arteries and veins carry
arteries carry oxygenated blood away from the heart
veins carry deoxygenated blood towards the heart
What are capillaries and their functions
Very tiny blood vessels connecting arteries to veins
one cell thick for rapid diffusion of nutrients and oxygen
Desrcibe the pathway of blood through the heart:
Deoxygenated blood returns to the heart via the vena cava
Right atrium contracts and blood flows into right ventricle
Right ventricle contracts and blood leaves through the pulmonary arteries to the lungs
Oxygenated blood from lungs enters the left atrium through the pulmonary veins
Left atrium contracts and blood flows into left ventricle
Left ventricle contracts and blood flows through the aorta to the rest of the body
What is the special characteristics of red blood cells
Biconcave shape to increase surface area to volume ratio to release oxygen faster
Contains haemoglobin to carry oxygen
Lacks nucleus to carry more haemoglobin
Desrcibe the exchange of gases in the lungs
Blood entering the blood capilary has high concentration of carbon dioxide and low concentration of oxygen
Carbon dioxide diffuses out of the bloodstream into the lungs. Oxygen from the surrounding air enters the lungs and diffuses into the blood stream
Blood leaving the blood capilary has high concentration of oxygen and low concentration of carbon dioxide
