SECTION B RESPIRATION Flashcards
What is respiration?
Respiration is the process by which energy is released from food by all living cells.
Respiration is catalyzed by enzymes.
How is ATP made?
ATP + phosphate reverse rxn ATP
What are the advantages of ATP?
- The energy can be released rapidly.
- Only a small amount of energy is released when each ATP molecule is broken down. This prevents waste since it allows the release of exactly the right amount of energy when needed.
- Energy can be released exactly where it is needed in the cell.
- Energy released by ATP is used by cells to manufacture proteins, DNA, for cell growth and repair, cell division, in active transport and for special functions like contraction of muscle cells and the transmission of nerve impulses.
What is aerobic respiration?
Aerobic respiration uses oxygen and takes place in the mitochondria. It always produces carbon dioxide, water and 38 ATP molecules per molecule of glucose.
glucose + oxygen (enzymes in mitochondria) = carbon dioxide + water + energy
C6H12O6 + 6O2 = 6CO2 + 6H2O + energy
What is anaerobic respiration?
Anaerobic respiration happens without oxygen in the cytoplasm of cells and produces less energy per molecule of glucose than aerobic respiration.
Anaerobic respiration in yeast cells
Yeast cells perform anaerobic respiration known as fermentation. It produces ethanol, carbon dioxide and 2 ATP molecules per molecule of glucose.
glucose (enzymes in cytoplasm) = ethanol + carbon dioxide + energy
C6H12O6 = 2C2H5OH + 2CO2 + energy
Anaerobic respiration in muscle cells
During strenuous exercise when the oxygen supply to muscle cells becomes too low for the demands of aerobic respiration the cells begin to respire anaerobically. This produces lactic acid and 2 ATP molecules per molecule of glucose.
glucose (enzymes in cytoplasm) = lactic acid + energy
C6H12O6 = C3H6O3 + energy
Lactic acid builds up in the muscle cells and begins to harm them causing fatigue and eventually collapse as they stop contracting. The muscle cells are said to have built up an oxygen debt. This debt must be repaid directly after exercise by resting and breathing deeply so that the lactic acid can be respired aerobically.
Anaerobic respiration in certain bacteria
Bacteria obtain energy by breaking down organic waste anaerobically to produce biogas.
What is gaseous exchange?
Gaseous exchange is the process by which oxygen diffuses into an organism and carbon dioxide diffuses out through respiratory surface.
What is breathing?
Breathing refers to the movements in animals that bring oxygen to a gaseous exchange surface and remove carbon dioxide from the surface. Breathing is not respiration.
Why is breathing and gaseous exchange important to organisms that respire aerobically?
To ensure organisms have a continual supply of oxygen to meet the demands of aerobic respiration and to ensure that the carbon dioxide produced in respiration is continually removed so that it does not build up and poison cells.
What adaptations do gaseous surfaces have that make them efficient?
- Large surface area so that large quantities of gases can be exchanged.
- Very thin so that gases can diffuse through them rapidly.
- Moist so that gases can dissolve before they diffuse through the surface.
- Rich blood supply to quickly transport gases between the surface and the body cells.
How does breathing and gaseous exchange happen in humans?
Gaseous exchange occurs in the lungs of humans. Humans have two lungs composed of many bronchioles (air passages) and many alveoli (air sacs). Each lung is surrounded by two pleural membranes which have pleural fluid between and a single bronchus leads into each from the trachea. Each lungs receives blood from the heart via a pulmonary artery and blood is carried back to the heart via a pulmonary vein. The two lungs are surrounded by the ribs which form the thorax (chest cavity). The ribs have intercostal muscles between and the diaphragm stretches across the floor of the thorax. Movements of the ribs and diaphragm brought about by the muscles contracting and relaxing cause air to move in and out of the lungs. The walls of the alveoli form the gaseous surface. Each alveolus has a wall that is one cell thick, is lined with moisture and is surrounded by a network of capillaries. As the air is drawn in during inhalation it is warmed in the nasal passages and cleaned and moistened by mucus lining the nasal passages and trachea. The mucus is moved to the throat by cilia lining the nasal passages and trachea and is swallowed. The air passes through the bronchi and bronchioles and enters the alveoli where gaseous exchange occurs between the air and the blood in the capillaries.
Gaseous exchange surface of fish?
Gaseous exchange occurs in the gills of. fish. A bony fish has four gills at each side of its head. Each gill has two rows of long, thin, fingerlike projections called gill lamellae. The walls of the gill lamellae form the gaseous exchange surface. Each lamella has a wall that is one cell thick, is moist since it has water passing over it as the fish breathes and has a dense network of capillaries down the centre.
Gaseous exchange in flowering plants?
Gaseous exchange occurs in the leaves, stems and roots of plants by direct diffusion between the intercellular air spaces and all the cells in these organs that are in contact with the air spaces. Gases diffuse between the atmosphere and the air spaces through the stomata of leaves and the lenticels of bark covered stems and roots. Lenticels are small areas of loosely packed cells. The walls and membranes of all cells inside the leaves, stems and roots of plants form the gaseous exchange surface. The direction of movement of gases depends on whether the organ of the plant is also carrying out photosynthesis. Movement of gases onto and out of photosynthesizing organs mainly leaves depend on the time of the day. The rate of respiration remains almost constant throughout the day and night but the rate of photosynthesis changes. During the night, only respiration occurs. Oxygen diffuses in and carbon dioxide diffuses out. As dawn approaches photosynthesis begins and its rate gradually increases. The compensation point is reached when the rate of photosynthesis equals the rate of respiration. At this point there is no net movement of gases in or out of leaves. During the day the rate of photosynthesis is greater than the rate of respiration. Carbon dioxide diffuses in and oxygen diffuses out. At about dark a second compensation point occurs as the rate of photosynthesis and respiration becomes equal once more. Only respiration occurs in non photosynthesizing organ like stems and roots. Oxygen diffuses in and carbon dioxide diffuses out all the time.
Cigarettes?
Nicotine addiction - nicotine is toxic and continued inhalation decreases appetite, increased heart rate and blood pressure and increases the risk of stroke and osteoporosis.
Reduced oxygen carrying capacity of the blood. Carbon monoxide combines more readily with haemoglobin than oxygen does which reduces the amount of oxygen carried to body cells. This reduces respiration and the smoker’s ability to exercise. In a pregnant woman it deprives the foetus of oxygen reducing growth and development.
A persistent cough - cigarette smoke causes mucus production to increase and the cilia to stop beating. Persistent coughing occurs to try and remove the extra mucus.
Chronic bronchitis - develops when cigarette smoke irritates and inflames the walls of the bronchi and bronchioles. This together with the increased mucus production causes the airways to become obstructed making breathing difficult.
Emphysema - develops when cigarette smoke causes the walls of the alveoli to become less elastic and the walls between the alveoli to breakdown which decreases their surface area. This reduces gaseous exchange makes exhaling difficult and causes air to remain trapped in the lungs. The bronchioles often collapse when exhaling obstructing the airways making exhaling even harder.
Cancer of the mouth, throat, oesophagus or lungs - Tar and other chemicals in cigarette smoke are carcinogenic causing tumors to develop in the respiratory system which replace normal and healthy tissue.
Chronic bronchitis and emphysema are two types of chronic obstructive pulmonary disease (COPD).
Marijuana?
A persistent cough Bronchitis Frequent acute lung infections due to marijuana reducing the body's ability to fight infections. Lung cancer Marijuana addiction
An athlete suffered muscle cramps following his race. The muscle cramps are MOST likely caused by an accumulation of
(a) urea
(b) oxygen
(c) lactic acid
(d) excess glucose
(c) lactic acid
