Transpiration And Plant Minerals Flashcards
What is transpiration
The loss of water from the leaves of a plant which mostly occurs from the underside of a leaf where there are many stomata in the epidermis
Transpiration stream process
-water evaporates from the leaves out of the stomata which decreases the water potential of the air space inside the spongy mesophyll
-water moves into the air spaces from the adjacent cells
-water moves out of the xylem into the cells in the leaves to replace lost water
-water hydrogen bonds to itself (cohesion) and hydrogen bonds to the walls of the xylem vessel (tension) resulting in capillary action
How does the stomata open
Guard cells turgid (full of water) as water moves into the vacuoles by osmosis and as the outer wall is more flexible than the inner wall the cell bends and opens the stomata
How does the stomata close
When guard cells flaccid as water moved out of vacuoles by osmosis and as outer wall is more flexible than the inner wall the cells bend back and close the stomata
What are the four factors affecting rate of transpiration and how does each effect
-light intensity(increases the rate of photosynthesis so the stomata open so water diffuses out of the leaf)
-temperature(increases molecular movement so more water molecules evaporate from cell surfaces and the rate of diffusion of water molecules from the leaf is increased)
-humidity(higher the humidity the lower the concentration gradient for water to move out the leaf)
-wind(removes water vapour from leaf surfaces so more water diffuses from the leaf)
How to treat mineral deficiency in plants
-test for specific mineral is deficient and then treat plant with this mineral
-add NPK fertiliser
What are the mineral ions in NPK fertiliser
Nitrogen, phosphorus and potassium
Uses of nitrate ions and what deficiency causes
-glucose and nitrate ions together make amino acids which make proteins which are essential for growth and repair of tissue
-deficiency causes chlorosis in which leaves turn pale yellow and growth slow
Use of phosphate ions and symptoms of deficiency
Involved in respiration and growth(cell division as phosphate group in DNA and RNA) and energy storage in form of ATP
-leaves have purple tint and curled and smaller than normal
Uses of magnesium and symptoms of deficiency
-essential for chlorophyll synthesis and so photosynthesis as absorbs light
-deficiency causes yellowing leaves and stunted growth as less photosynthesis so less energy released by respiration
Root hair cell function and how are root hair cells adapted for their function
Absorb water amd mineral ions from soil
-large surface area, thin walls and are close to xylem cells used for transporting water up plant, many mitochondria which provides energy for active transport of mineral ions
How do mineral ions move into root hair cell
Moved by active transport using carrier proteins on root hair cell surface that pick up the minerals and change shape to move them against the concentration gradient
Uses of potassium ions and deficiency symptoms
-respiration and photosynthesis and regulate water balance and osmotic pressure
-weak stems and stalks, yellowing leaf edges as maintains cell turgor and regulates water movement
Role of calcium ions and deficiency symptoms
Component of cell wall, stunted growth first on younger leaves
