Flashcards for AQA A Level Biology Chapter 2- Nucleic Acids
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Course
Chapter 6- Exchange
Institution
AQA
Contain all you need to know for this chapter of the course. Are detailed and concise, and work best with Anki, but can be used with quizlet. They are in the form of a txt document that can be imported into anki or quizlet. Some images are missing due to the format, so these images will have to be ...
"""What is Fick's Law?""" Rate of diffusion is directly proportional
to:<div>surface area x concentration gradient/length of diffusion path</div>
What is the structure used for insect gas exchange? Tracheae- a network of tubes
supported by strengthened rings. These divide into smaller tubes called tracheoles
and extended throughout all of the tissue of the insect.
What are the three ways gases are exchanged in insects? Along a diffusion
gradient- as cells respire the concentration of oxygen falls, so a gradient is
created. The concentration of CO<sub>2 </sub>increases, creating another gradient,
thus causing oxygen to flow in and carbon dioxide to diffuse out.<div>Insects can
contract their muscles to squeeze their trachea enabling movements of air in and
out</div><div>The ends of the tracheoles are filled with water- during anaerobic
respiration, lactate is released, which dissolves in the water, making its water
potential more negative in the cells, causing water to enter to move into the cells
by osmosis. As such, the pressure in the tracheole decreases, causing air to come
in </div>
How do gases enter insects? The opening and closing of spiracles
What is the name for the fish apparatus for gases exchange?Gills
How are gills structured? Gills have filaments that are stacked up like pages
in a book and that increase the surface area of the gills. Additionally, these
filaments have lamellae, which exist at a right angle to the filaments, further
increasing the surface area
What is countercurrent flow? """<img src=""""image-
735cba17d66328c768741cb9e5facb4d25e1614b.png""""><br><div>Since the blood and water
are flowing in opposite directions, blood with lots of oxygen meets water with lots
of oxygen, meaning a concentration gradient still exists. It also means the
concentrations of oxygen in both blood and water does not equilibrate</div>"""
How is water loss limited in insects? Closing of spiracles<div>Waterproof
cuticle on the surface of their skeleton</div>
How is water loss limited in plants? A thick waxy cuticle<div>Rolling up of
leaves to decrease surface area</div><div>Hairy leaves to trap moist air next to
the leaf, decreasing the concentration gradient</div><div>Stomata in sunken pits,
meaning moist air stays above the stomatum</div><div>A reduced surface area of
leaves e.g. spines</div>
What are plants that live in dry conditions called? Xerophytes
What is the process of inspiration? External intercostal muscles
contract<div>Internal intercostal muscles relax</div><div>Diaphragm
contracts </div><div>Ribs are pulled upwards and
outwards </div><div>Increasing the volume of the thorax, pressure decreases,
air flows in</div>
What is the process of expiration? External intercostal muscles
relax<div>Internal intercostal muscles contract</div> <div>Diaphragm relax</div>
<div>Ribs are pushed downwards and inwards </div> <div>Decreasing the volume
of the thorax, pressure increases, air flows out</div>
"""Label this:<div><img src=""""image-
e543866bda88d3669ffaba7d6c96b27cb8b61241.png""""><br></div>""" """<img
src=""""image-550efee847a970fbad0e2176c3566ecca04d1290.png"""">"""
What are the two types of digestion Mechanical/physical<div>Chemical </div>
How are carbohydrates chemically digested? Amylase breaks up the long
polysaccharide chain into disaccharides<div>These disaccharides are broken up into
monosaccharides by membrane bound disaccharidases like maltase and sucrase</div>
How are proteins chemically digested? Endopeptidases hydrolyse peptide bonds
inside polypeptide chains forming smaller polypeptide
chains <div>Exopeptidases hydrolyse the amino acids on the edges of these
small polypeptide chains</div><div>Membrane bound dipeptidases split two amino acid
molecules bound together into one amino acid molecule</div>
What membrane are membrane bound dipeptidases bound to? The ileum
What are the two purposes of the bile? To make the output of the stomach
neutral, as bile is alkaline <div>To emulsify lipids into lipid
droplets </div>
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