B6, 10-12 Flashcards
6 uses of glucose
- Produce energy through respiration
- Changed into sucrose to be transported (in the sap of phloem tubes)
- Changed into starch to be stored (in leaves/roots)
- Changed into cellulose to form cell wall
- Changed into amino acids, when combined with nitrates
- Changed into oil to be stored in seeds
- provide a good store of energy for germination
Ways to overcome limiting factors in glasshouses
Carbon dioxide concentration:
- increase by burning carbon-based fuels (eg. natural gas, propane) or direct from gas generator
Light intensity:
- install artificial lighting system to control light intensity and quality of light (red/violet wavelength)
Temperature:
- install sensor that is connected to a heater to make necessary adjustments when there are changes to temperature
Ways a pathogen for a transmissible disease may be transmitted
- Direct contact
- infected person’s blood comes into contact with another person’s blood/body fluids; eg. AIDS, athlete’s foot - Indirect transmission
- from the air, through the respiratory passage (breathing in droplets); eg. flu, whooping cough
- from contaminated food/water; eg. poliomyelitis, cholera
- from animals, by vectors; eg. dengue, malaria, rabies
Body defences - mechanical barriers
- Hairs in nose trap dust that might be carrying pathogens
- Skin has a thick outer layer of dead cells which is very difficult to penetrate
- Skin secretes sebum that has oil and acid to prevent pathogen growth
- When skin is cut, blood clots prevent entry of pathogens
- Tears and saliva contain enzymes that kill bacteria, to protect eyes and mouth
Body defences - chemical barriers
- Mucus found along alimentary canal, respiratory passage and urinary tract can trap pathogens
- in respiratory passages, cilia can sweep mucus back up to throat to be swallowed - Hydrochloric acid in stomach kills bacteria in food and in swallowed mucus
Antibody production by lymphocytes
- Pathogens enter body
- One of the many lymphocytes recognises specific antigens on pathogen
- Lymphocyte divides rapidly by mitosis
- Lymphocytes produce specific antibodies that bind with antigens
- Antibodies destroy pathogens
* a foreign/non-self antigen will cause an immune response
Differences between active immunity and passive immunity
Active immunity
1. When a person has made their own antibodies and memory cells that protect against a disease
2. Gained after an infection by a pathogen or by vaccination
3. Long-term immunity
Passive immunity
1. Memory cells are not produced
2. When a person receives antibodies made by another organism
3. Short-term immunity
Importance of passive immunity for breast-fed infants
Baby’s immune system is not well developed, so mother’s antibodies can protect it against diseases she is immune, for the first few months of its life
Vaccination process
- When injected with vaccine (substance containing weakened/dead pathogens), the body recognises specific antigens as harmful and an immune response is triggered
- Lymphocytes multiply and produce specific antibodies to bind with antigens
- Lymphocytes also make memory cells that provide active immunity (long-term immunity)
- If exposure to same pathogen, there will be a rapid immune response (memory cells will be able to quickly produce antibodies)
4 important factors in controlling the spread of disease
- Hygienic food production
- Good personal hygiene
- Waste disposal
- Sewage treatment
What are the body’s defences besides mechanical and chemical barriers?
- Cells
- Phagocytes digest pathogens by phagocytosis
- Antibody production by lymphocyte - Can be enhanced by vaccination
Example of auto-immune diseases
Type 1 diabetes: where beta cells in pancreases are attacked and destroyed, affecting insulin production, so blood glucose concentration is not controlled
- needs injection of insulin regularly
5 features of gas exchange surfaces (alveoli walls)
- Many alveoli
- provide a large surface area for diffusion - Thin surface
- alveolus wall is only one cell think for shorter distance of diffusion - Large network of capillaries
- increases surface area for diffusion
- good blood supply to take gases to and from the exchange surface - Good ventilation of air
- presence of ventilation brings in air to allow oxygen exchange to happen - Film of moisture
- lining of alveoli is coated with a film of moisture for gases to dissolve in for faster diffusion
What happens during inhalation?
- External intercostal muscles contract
- Rib cage moves upwards and outwards
- Diaphragm contracts and flattens
- Volume in thorax increases
- Pressure in thorax decreases
What happens during exhalation?
- Internal intercostal muscles contract
- Rib cage moves downwards and inwards
- Diaphragm relaxes and curves
- Volume in thorax decreases
- Pressure in thorax increases
