2.1 a + b - Transport and Exchange

What do living cells need and why?

O2 for aerobic respiration, glucose/fatty acids as respiratory substrates, amino acids for protein synthesis, ions maintain water potential, water as solvent

What do living cells need to dispose of and source?

CO2 from aerobic respiration, O2 from photosynthesis, urea/ammonia from excess amino acids

What do plant tissues need?

O2, CO2, inorganic ions, water

Fick’s law

If temp constant, diffusion rate determined by SA, conc difference and diffusion distance

Features of exchange surfaces

large SA:V ratio, thin surface, large conc gradient, moist surface, permeable to gases

Function of xylem tissue

transport water/mineral ions from roots to leaves

Function of phloem tisssue

transport of sucrose to roots/growing regions

Function of circulation in mammals

transport of O2, CO2, glucose, amino acids, lipids and urea in blood system

Define compensation point

rate of photosythesis equal to rate of respiration

Adaptations of leaves for gas exchange

large SA, steep conc gradient, stomata allow gase entry, thin so small diffusion distance

How does gas exchange in mammals take place?

diffusion. Aerobic respiration uses O2 producing CO2 creating conc gradient so O2/CO2 diffuse in/out

Adaptations of alveoli

many alveoli so large SA, speed conc gradient maintained by rich blood supply, one cell thick epithelium, moist allowing gases to dissolve

What is emphysema?

tar damages alveolar walls so fewer alveoli, reduced SA, less gas exchange. Elastic lining breaks down so alveoli can’t recoil. Residual air trapped so fresh air can’t reach exchange surfaces

What is bronchitis?

inflamed bronchial tubes and mucus production reduces air flow. Tar paralyses cilia, mucus/microbes not removed increasing infection risk

What is rate of respiration expressed as?

O2 absorbed or CO2 produced in given time

How to measure oxygen uptake

respirometer

How is rate of respiration found in Respirometer?

distance moved by coloured water droplet per minute

Rate of respiration equation

rate of respiration = volume of O2 absorbed / (time in minutes x mass of animal )