BIOLOGY POO

Posted by admin on January 23, 2018 in flash cards

Question Answer
Important function of tissues in plants Obtaining energyProducing organic compounds Distributing materialsRemoving wastes and exchanging gases
Root system below ground absorb water and nutrients from soil
Shoot system parts above ground responsible for transportation of resources, absorption of gases, reproduction and photosynthesis
Two categories of plants Non – vascular plants – do not have vascular tissueVascular plants – vascular tissue present
2 types of vascular tissue Xylem and Phloem
Xylem – carries water and dissolved nutrients from roots to the rest of the plant2 types of cells: tracheids and vessel elementsAs xylem cells mature, they die leaving hollow cells supported by the remaining cell walls
Phloem Transports sugar and other plant products from the site of production to the leaves and rest of the plant2 types of cells : sieve tube cells and companion cells which have no nuclei, mitochondria, or vacuoles.
2 main processes that take place in plant cell PhotosynthesisCellular respiration
Roots of plants have several functions Absorb water and minerals from the soilSupport and anchor plantMain storage tissue
Root surface Surface area is greatly increased by the presence of root hairsA root hair is an extension of each root epidermal cell that makes up the epidermis .
Root hair (beneath epidermis) Beneath the epidermis there are thin walled parenchyma cellsThese cells make up the cortex that constitutes the main root bodyIn the centre there is a core of vascular tissue that consists of xylem cells
Once inside root hair water moves to the parenchyma cells and into the xylem vesselForce of water entering the root and pushing its way into the cell creates pressure. This pressure is known as root pressure.
Water moves up the shoot system The way water moves up the shoot system involves many connected processes : adhesion and cohesion forcesThe continuous column of water through the plant is known the transpiration stream
transpiration Constant upwards movement is driven by the evaporation of water from the leaves.
transpiration pull Process where water is moved up a large vertical distance through the xylem
Water stress When a plant loses more water through transpiration than it takes up it wilts
GAS EXCHANGE Oxygen and carbon dioxide are exchanged locally through the plantOccurs through passive diffusionNo transport is required
stomatal pores remarkable adaptations that control the exchange of gases and controls the amount of water loss during the dayStomata are mostly located in the lower epidermis of a leafEach pore is bordered by guard cells
Stomatal open and close Stomata pore will open when the guard cell absorbs waterPore closes when it loses water
OBTAINING AND TRANSPORTING NUTRIENTS Nutrients refer to substances such as minerals and vitamins.Plant nutrients are soluble minerals and salts such as sodium, potassium and phosphorus.Required for the complex chemistry that runs every cell.
Translocation Translocation is the movement of sugars in solution through the plant.
Phloem and Translocation Energy required – cellular respiration in mitochondria of companion cells.Concentration of sugar in the phloem increases.Water moves from xylem to sieve cells by osmosis.
Waste Removal Deciduous plants store wastes in leaves which drop off in autumn.Non-deciduous trees remove salt also by leaf fall.Plants with bark can transfer unwanted material via the phloem to the bark before shedding.

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