Multicellular Organisms 2
How are carbon dioxide and oxygen exchanged through alveoli?
Oxygen and carbon dioxide molecules from high concentration to low concentration. Oxygen molecules enter the alveoli and move to low concentration within red blood cells flowing through attached capillary. Carbon dioxide is mostly removed from red blood cells as it passes across the alveoli and exhanled.
Air movement through different parts of respiratory system?
Mouth/nose - trachea- bronchi- bronchioles - allveoli
How are plants able to exchange materials?
The presence of stoma which are opened and closed by guard cells. When open, gases can diffuse into the plant. When closed, less carbon dixiode is avalible for photosynthesis.
What factors imapct material exchange in plants?
- Decrease in carbon dioxide concentration within leaf can make stoma open.
- Humidity makes stoma stay open
- Enviornmnetal factors such as light stimulus and heat making guard cells lose water, causing the stoma to close.
How are gases exchanged by the stoma? Why?
Through passive diffusion as carbon dioxide passes through thin membrane of stomata from high concentration outside the plant to low concentration within. This happens so CO2 can be converted into glucose for areobic respiration.
What are the structural and functional leaf features for exchange of materials?
- All parts of plant can exchange gases.
- Large and flat leaves maximise surface area.
- Open air spaces in leaves provide great surface area and less distance for diffusion of gases.
Why does the presence of air spaces in the spongy mesophyll assist diffusion of carbon dioxide through a leaf?
It means the CO2 concentration can increase enabiling it to diffuse further into the leaf.
What is the role of the respiratory system?
Permits entry of oxygen into blood for transport to cells of all organ systems.
What is the role of the digestive system?
Break down of food into products that are absorbed and passed into bllood for transport to the cells of all organs.
What is the role of the cicrulatory system?
Transport oxygen and products of digestion to the cells of all organ systems.
Describe the gas exchange that occurs in a leaf during bright sunlight as opposed to night.
During bright sunlight, the stomata opens increasing the rate of gas exchange at leaves. At night, the stomata takes in oxygen for aerobic respiration. This produces carbon dioxide so it diffuses out of the leaf.
What is the exchange surface on the small intestine assisting absorption of nutrients? Structures allowing for this funciton?
- Villus
- Microvilli along villus increase SA:V for faster absorption.
- Coated with fluid from epitheial cells.
- Thin one cell thick for efficent diffusion
- Rich blood supply
How do nutrients move across membrane into villi?
Diffusion, facilitated diffusion and active transport
Movement of nutrients in small intestine?
Diffuse from small intestine to blood.
What happens to digested glucose and amino acids?
Blood vessels within villi carry the nutrients away from small intestine to be used elsewhere within the body.
Order of digestion
Mouth - oesphagus - stomach - small intestine - large intestine - rectum
What are the accessory organs?
Pancreas - breaks down fat, protein and carbohydrates by producing enzymes.
Liver - produces bile to break down fat.
Gall bladder - stores bile
Structural features of mouth and function
Teeth - chewing for physical breakdown
Tounge - moves food in mouth directing to oesphagus
Saliva glands - produce saliva, containing digestve enzymes for chemical breakdown of food. Mucus also lubricates food.
Oesophagus is made of ...
Skeletal and smooth tissue.
Skeletal tissue stops food from coming back up.
Peristalsis occurs to assist food move through oesophagus.
Structural features of stomach and its functions.
- Made of muscle and epitheial tissue for mechanical and chemical digestion.
- Muscle tissue assists the physical churning process.
- Hydrochloric acid, protective mucus, digestive enzymes from epitheial tissue assist chemical break down.
Where does the majority of nutrient absorption occur?
95% occurs within the small intestine due to the efficient diffusion of nutrients to blood stream.
What is absorbed in the large intestine?
The colon absrobs salt, water and vitamins from digested mass.
Anything not digested is passed as faeces in the rectum.
What are enzymes?
Proteins within the body which are responsible for speeding up a reaction (catalyse biochemical reactions) withou taking place in the reaction. These enzymes are reusable and can have intracellular or extracellular actions.
How do enzymes work?
- An enzyme and substrate tightly bind to form an enzyme-substrate complex. This binding brings vital atoms near each other, stressing convalent bonds.
- This causes a chemical reaction in the active site which forms the product, allowing the enzyme to work again.
What does the 3D structure of an enzyme determine?
Determines the shape of the active site; determines the specifity of the enzyme, enabling reactions to go faster by lowering the amount of energy needed.