Topic 6 - Plant Structures And Their Function Flashcards
(64 cards)
What is photosynthesis?
A chemical reaction that takes place inside photosynthetic organisms converting light energy into chemical energy
Endothermic
Word equations photosynthesis
Carbon dioxide + water —> glucose + oxygen
Write symbol equation for photosynthesis
6CO2 + 6H20 —> C6H12O6 + 6O2
Why is photosynthesis important?
It produces glucose which has a wide range of uses:
Used in respiration to release energy
Converted to starch and stored - broken down to glucose when plants need energy
Used to make complex organic molecules which are used for growth, making up an organism’s biomass
Where does photosynthesis take place?
Within chloroplasts
What type of reaction is photosynthesis?
An endothermic reaction that takes in energy (in the form of light)
What is chlorophyll
A pigment found in chloroplasts that absorbs light.
Describe the two main stages of photosynthesis
Chlorophyll absorbs energy (from the light from the sun) which is used to split water intp oxygen gas
Carbon dioxide combines with hydrogen ions to form glucose
Why do plants require water?
Photosynthesis
Maintaining of structure (turgidity/rigidity)
Cooling effect
Why do plants require mineral ions?
For growth e,g nitrates are required to produce proteins
Which structure in plants is adapted for the uptake of water and minerals?
Root hairs
How is water transported into root hairs?
Lower concentration of water in root hair cells than in the soil
Water diffuses down its concentration gradient into root hair cells by osmosis
How are minerals transported into root hair
Lower concentration of mineral ions in the soil than in root
Root hair cells take up mineral ions by active transport
Outline how plants roots are adapted for the absorption of water and minerals
Plant roots are composed of millions of root hair cells which have:
Long hairs that extend from the cell body, increasing surface for absorption
Many mitochondria which produce ATP for active transport of mineral ions
Name the two plant transport tissues
Xylem
Phloem
What is the function of the xylem?
Transports water and minerals up the plant, from the roots to the leaves via transpiration stream
Describe how the xylem is adapted to its function
Composed of dead cells laid end-to-end to form a long, hollow, continous column
No end walls which provide little resistance to the passge of water
Thick cell wall strengthened with lignin to provide support
What is function of the phloem?
Transports sugars up and down the stem from photosynthetic tissues ( e,g mature green leaves) to non-photosynthetic (e,g developing seeds) via translocation
What are two cells types that make up the phloem?
Sieve tube elements
Companion cells
Describe how phloem is adapted to its function
Sieve tubes elements are long, thin cells, laid end-to-end with perforated end plates to enable the flow of sugars. They contain no nucleus and little cytoplasm to allow sugars to flow easily.
Companion cells (adjacent to sieve tubes elements) contain a dense cytoplasm, nucleus and mitochondria. They provide energy for processes in both cell types.
What is transpiration?
The loss of water vapour from the parts of a plant exposed to air due to evaporation and diffusion.
Where does the majority of transportation take place?
Leaves
Describe the process of transpiration?
Water evaporates from the mesophyll cell surfaces and diffuses out of the stomata. Water molecules (which have cohesive properties) are drawn up the xylem vessels to replace the water that has been lost This causes more water molecules to be absorbed from the soil into root hair cells.
How does the transpiration stream transport mineral ions?
Mineral ions are dissolved in water that is carried by the transpiration stream.
