9.1 Transport in Xylem of Plants

Jasmine Wells
Flashcards by Jasmine Wells, updated more than 1 year ago
Jasmine Wells
Created by Jasmine Wells over 5 years ago
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International Baccalaureate Biology (9. Plant Biology) Flashcards on 9.1 Transport in Xylem of Plants, created by Jasmine Wells on 01/04/2016.

Resource summary

Question Answer
What is the order of the plant family tree? Remember: King Philip Came Over For Good Sex Kingdom Phylum Class Order Family Genus Species
What are Angiospermophytes? Flowering plants
What are Monocotyledonous plants? Plants that have one cotyledon (One seed leaf). E.g. Grass
What are Dicotyledonous plants? Plants that have 2 cotyledons (2 seed leaf) e.g. Roses
Give 5 features of a monocotyledonous plant. - Parallel veined leaves - One cotyledon after germination - Random structure of vascular bundle - Adventitious roots - Floral organs in multiples of 3
Give 5 features of a dicotyledonous plant. - Branched roots - Branched veins in leaves - Structured vascular bundle - 2 cotyledons after germination - Flowers in multiples of 4 or 5
What is meant by transpiration? Transpiration is the loss of water vapour from the stems and leaves of a plant. It is the inevitable consequence of gas exchange (from photosynthesis) in the leaf.
What is the word and chemical equation of photosynthesis? Word: Carbon Dioxide + Water (With the help of sunlight and chlorophyll) -> Glucose + Oxygen Chemical: 6CO2 + 6H2O -> C6H12O6 + 6O2
How does transpiration occur? - Leaves must use carbon dioxide to photosynthesise and release oxygen as a waste product. - When this occurs, small pores known as stomataon the surfaces of the leaf, surrounded by guard cells open and close allowing these gases to exit and enter. - As a consequence, water vapour also escapes the surface of the leaf - also known as transpiration occuring.
How do plants minimise water loss? Through the help of guard cells. Guard cells are on either side of each stomata and control the aperture of stomata, enabling it to open and close where appropriate.
Factors that affect transpiration and their relationship to its speed. - Temperature (Greater amount of heat = greater amount of transpiration) PROPORTIONAL - Humidity (An increased amount of water vapour surrounding the atomsphere will decrease the rate of transpiration.) INVERSELY PROPORTIONAL - Wind speed (greater wind speed = greater rate of transpiration up to an extent).
What is cohesion? (of water) Cohesion holds hydrogen bonds together to create surface tension on water.
What is adhesion? (Of water) Adhesion occurs when water is attracted to other molecules which causes the water to be "pulled" towards them.
Why is water attracted to water? Due to the positve and negative charges of water molecules ie. Hydrogen have positive charge and oxygen have negative charge. Hydrogen atoms of one water molecule are attracted to the oxygen atoms of another water molecule - allowing the attraction to occur.
How do structure of xylem help withstand low pressures? Xylem vessels are continuous tubes lined along their walls is a substance called lignin. The cohesion and adhesion properties of water allow a continuous stream of water to be pulled up from xylem, without collapsing.
How does tension in a leaf wall maintain the transpiration stream? When water evaporates from a leaf's surface, adhesion causes water to be drawn through cell wall from nearest supply to replace the water lost by evaporation. Tension can be maintained from one water molecule to the other because of cohesive property of water.
How does active transport of minerals in the roots work? Water is absorbed into root cell by osmosis, because solute concentration in root hair cell is greater than the solute concentration of soil. Concentration gradients are established by active transport using protein pumps in cell membranes.
4 adaptions of plants in deserts (xerophytes) - Very thick waxy cuticle covering the stem - to minimise water loss - Vertical stems: To absorb sunlight early, and late in the day but not at midday - Spines instead of leaves: To reduce surface area for transpiration - Stems contain water storage tissue: And become swollen after rainfall.
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