Edexcel IGCSE Biology Gas Exchange

This page contains the detailed and easy notes for Edexcel IGCSE Biology Gas Exchange for revision and understanding.

HUMAN GAS EXCHANGE SYSTEM

MECHANISM OF BREATHING

GAS EXCHANGE

ALVEOLI

GREATER SURFACE AREA

SHORTER DIFFUSION DISTANCE

STEEP CONCENTRATION GRADIENT

ORGANISATION IN PLANTS

CELLS

TISSUES

  • Xylém and Phloem
  • Palisade mesophyll tissue
  • Spongy mesophyll tissue

ORGANS – Root, Stem and Leaves

ORGAN SYSTEM – Water Transport System

ORGANISM

TRANSPIRATION

  • Transpiration is the loss of water from the surface of the leaves in the forms of water vapours.
  • In plants it takes place through the stomata.

FACTORS AFFECTING TRANSPIRATION

MEASURING RATE OF TRANSPIRATION

  • Potometer is the device which is used to measure the rate of water uptake or the rate of transpiration.
  • The movement of bubble is an indicator of water movement which in turn shows the rate of transpiration

ADAPTATIONS TO LIMIT TRANSPIRATION

  • Cuticle layer on the leaf which is waterproof prevent rate of transpiration
  • Stomata are present on the lower surface to reduce rate of transpiration.
  • Some plants stomata open is night and closes in day.
  • In plants like cactus the leaves are reduced to spines to decreases the surface area for water loss.
  • Some plants have sunken stomata.

DISCLAIMER

Disclaimer: I have tried by level best to provide the answers and video explanations to the best of my knowledge. All the answers and notes are written by me and if there is any similarity in the content then it is purely coincidental. But this is not an alternative to the textbook. You should cover the specification or the textbook thoroughly. This is the quick revision to help you cover the gist of everything. In case you spot any errors then do let us know and we will rectify it.

References:

BBC Bitesize

Wikipedia

Wikimedia Commons