Biology: Transpiration, Transport & Support in Plants Past Paper PDF
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This document is a review of transpiration, transport, and support in plants. It covers various factors like humidity, temperature, and light intensity that affect the rate of transpiration. It also describes the structural adaptations of plants to reduce water loss, and the significance of xylem and phloem in the transport processes. The document is suitable for secondary school biology students.
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🐾 Biology: Transpiration, transport and support in plants Pastpp review Transpiration plant loses water by evaporation of water vapour Transpiration pull Biology: Transpiration, transport and support in plants Pastpp r...
🐾 Biology: Transpiration, transport and support in plants Pastpp review Transpiration plant loses water by evaporation of water vapour Transpiration pull Biology: Transpiration, transport and support in plants Pastpp review 1 draw water by osmosis lose by diffusion of water vapour Significance Creates transpiration pull to transport water and dissolved minerals up xylem Helps absorption of water and dissolved minerals Promotes evaporation to lose heat Factors higher relative humidity reduce concentration gradient of water vapour temperature 1. higher temperature causes water to evaporate faster 2. air can hold more water at higher temperature→increase concentration gradient Biology: Transpiration, transport and support in plants Pastpp review 2 air movement wind carries away water vapour water vapour no longet accumulate around stomata steeper concentration gradient light intensity light: stomata open→water vapour diffuses out at a higher rate+ leaf temperature increases dark: stomata close→only a few water vapour can diffuse out leaf surface area more stomata Density of stomata Land plants: fewer stomata on upper epidermis to reduce water loss Submerged plants: few or no stomata as not covered by cuticle→directly diffuse in Floating plants: only on upper epidermis; lower note covered by cuticle→directly diffuse in Adaptations to reduce water loss Impermeable waxy cuticle reduces evaporation of water Guard cell close stomata when dehydrated Upper epidermis fewer stomata as directly hit by sunlight + higher temperature Xylem Biology: Transpiration, transport and support in plants Pastpp review 3 transport water and minerals non-living Biology: Transpiration, transport and support in plants Pastpp review 4 Phloem Distribution of vascular bundle Biology: Transpiration, transport and support in plants Pastpp review 5 Transport of water and minerals Biology: Transpiration, transport and support in plants Pastpp review 6 Translocation of organic substances(sucrose/ amino acid) Leaves down growing regions(buds, root tips) and storage tissues(fruits, roots) Turgidity of thin walled cells Eg pith, cortex Sufficient water: turgid cells press each other to provide a turgidity Biology: Transpiration, transport and support in plants Pastpp review 7 Not sufficient water: flaccid Rigidity of thick walled cells Mechanical support Eg xylem(thick cell walls and lignified, dead) Biology: Transpiration, transport and support in plants Pastpp review 8
