Higher Biology
Unit 1 – Respiration
Learning Outcomes
Cells
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Diffusion is the movement of a substance from a region of high concentration to a region of
lower concentration until evenly spread e.g. Glucose, Oxygen, Carbon Dioxide
Osmosis is the movement of water from a region of high water concentration to a region of
lower water concentration through a selectively permeable membrane
Active Transport is the movement of a substance from a region of low concentration to a
region of higher concentration and it requires energy e.g. sodium
If a substance is Hypotonic to whatever it is being compared, it has a higher water
concentration. Handy Hint – HypOtonic = mOst water
If a substance is Isotonic to whatever it is being compared, it has the same water
concentration.
If a substance is Hypertonic to whatever it is being compared, it has a lower water
concentration.
Animal cells burst in hypotonic solutions
Animal cells shrink in hypertonic solutions
Plant cells become turgid in hypotonic solutions
A plant cell does not burst because it has a cell wall
Plant cells become plasmolysed, and the tissue feels flaccid in hypertonic solutions
Plasmolysed is when the vacuole loses so much water it pulls the plasma membrane (cell
membrane) and cytoplasm away from the cell wall
The cell wall is made of Cellulose and is freely permeable
The cell membrane is made of Proteins and Phospholipids and is selectively permeable
The cell membrane is also called the plasma membrane and the model of it is called the
Fluid Mosaic Model.
The cell membrane is said to be fluid as it is constantly moving
The cell membrane is said to be like a mosaic as proteins are scattered through it
Proteins in the cell membrane have many different jobs – they can form channels which
allow substances to pass through and they are enzymes for chemical reactions
Energy
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ATP is the chemical energy provider for all cells
ADP + Pi  ATP
This is called Phosphorylation
ATP is needed for activities such as nervous impulses, muscle contraction, sperm moving
Energy is released when ATP is broken down into ADP + Pi
Respiration
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A mitochondria is a cell organelle where respiration occurs
Respiration is the process in which we release energy from our food
Enzymes are required for Respiration to occur
The 3 stages of Respiration are Glycolysis, Krebs Cycle and the Cytochrome System
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The Respiration helpline Phone Number is – 632-65444
Glycolysis is an Anaerobic Process as no oxygen is required.
Glycolysis occurs in the cytoplasm of a cell
2 ATP are need for Glycolysis and 4 ATP are produced, so there is a net gain of 2 ATP
In Glycolysis, Glucose is broken down into Pyruvic Acid.
NAD is the hydrogen carrier and it carries the Hydrogen to the Cristae
Instead of Glucose, Fats and Proteins can be used as alternative respiratory substrates
Krebs Cycle is an Aerobic Process so it requires oxygen
The Krebs Cycle occurs in the central matrix of a mitochondrion
In the Krebs Cycle, the following conversions occur
Pyruvic AcidAcetyl Co ACitric AcidInt 5CInt 4CInt 4CInt 4C
Hydrogen is produced and combines with the carrier NAD and is taken to the cristae of a
mitochondria for the Cytochrome System
Carbon Dioxide is released in the Krebs Cycle
The Cytochrome system occurs in the cristae of a mitochondrion.
The Cytochrome system is an Aerobic Stage as oxygen is required
36 ATP are generated in the Cytochrome system
Hydrogen is passed through a series of reactions and the final hydrogen acceptor is
oxygen
Hydrogen and oxygen combine together to make water
If Anaerobic Respiration is occurring, only Glycolysis will occur and only 2 ATP will be
gained
If Aerobic Respiration is occurring, Glycolysis, Krebs Cycle and the Cytochrome System will
occur and a total of 38 ATP will be produced.