Unit 3A - Life Processes Flashcards
Why do water molecules pass both ways through the membrane during osmosis?
Because they are moving about randomly all the time and so some will be going from the are of low concentration to an are of high concentration
What’s the definition of osmosis?
Osmosis is the movement of water molecules across a partially permeable membrane from an area of high water concentration to an are of low concentration
How does water move in and out of cells?
By osmosis
If a solution is quite concentrated does it contain a lot of water?
No
What happens to water molecules when a cell is short of water?
The solution inside it is quite concentrated and so the concentration outside of it is more dilute, and so water will move into the cell by osmosis
What experiment can you do to show osmosis and what would you find?
Cut potato up into cylinders and place them in beakers of pure water and a very concentrated sugar solution, and measure their length before and after a few hours of being the beaker. If the cylinders have drawn in water by osmosis they will be longer, and if water has been drawn out they will have shrunk. The water will be drawn out in the rich sugar solution because the water concentration is higher in the potato
What are the three ways that substances can move?
By osmosis, diffusion and active transport
What do life processes need before they can happen?
Gases or other dissolved substances
What is the definition of diffusion?
Where particles move from an area of high concentration to an area of low concentration
What’s similar between diffusion and osmosis?
They both involve stuff moving from an area where there’s a high concentration of it to an area where there’s a low concentration of it
What is different about the way particles move in active transport compared to osmosis or diffusion?
Active transport involves particles moving from an area of lower concentration to an area of high concentration which is the opposite to diffusion and osmosis
What four ways are exchange surfaces adapted to maximise effectiveness?
- ) They are thin so substances have a shirt distance to diffuse
- ) They have a large surface area so lots of a substance can diffuse at once
- ) Exchange surfaces in animals have lots of blood vessel, so the substance can get into and out of the blood quickly
- ) Gas exchange surfaces are ventilated
How does carbon dioxide go from the air into the leaf for photosynthesis?
Carbon dioxide diffuses into air spaces in the leaf, and then it diffuses into the cells whee photosynthesis happens
What part of the cell does carbon dioxide diffuse through?
The stomata
What diffuses out of the stomata after photosynthesis has happened?
Oxygen and water vapour
What controls the size of the stomata?
The guard cells
Why are leafs a flattened shape?
To increase the area of gas exchange surface so that it is more effective
What conditions does evaporation happen fastest in?
Hot, dry, windy conditions
Why do humans so oxygen from the air?
For respiration
What part of the body are the lungs in?
The thorax
What part of the body separates the thorax and the abdomen?
The diaphragm
What protects the lungs?
The rib cage
How does gas get from the air to where the gas exchange takes place?
As you breathe in the air goes through the trachea, this splits into two tubes called bronchi, one going into each lung, the bronchi splits into smaller tubes called bronchioles, these finally end at small bags called alveoli which is where gas exchange takes place
What is ventilation?
The movement of air into and out of the lungs
What happens as you breath in?
Intercostal muscles and diaphragm contract, thorax volume increases, decreasing the pressure drawing air in
What happens when you breath out?
Intercostal muscles and diaphragm relax, thorax volume decreases, this increases the pressure so the air is forced out
What are artificial ventilators and who are they for?
Machines that move air into and out of the lungs, people who can’t breathe by themselves like if they are under general anaesthetic or have lung injury or disease
What was an old fashion artificial ventilator called?
An iron lung
How did an iron lung work?
They were a giant case from the neck to the abdomen, air was pumped out of the case, pressure dropped, the lungs expanded and so air was drawn in, when air was pumped into the case it has the opposite effect forcing air out of the lungs
What two parts of the body are adapted so that substances can diffuse through them most effectively?
Gas exchange in the lungs and how digested food gets from the gut into the blood
Where does the gas exchange take place in the lungs?
In the million of tiny air sacs called alveoli
What four ways are alveoli specialised to maximise the diffusion of oxygen and CO2?
- ) Enormous surface area
- ) Moist lining for dissolving gases
- ) Very thin walls
- ) A good blood supply
Roughly what is the surface are of all the alveoli in the body?
75m squared
What is the small intestine covered in?
Millions and millions of tiny projections called villi
What three ways are villi specialised for absorbing food?
- ) large surface area so that food is absorbed more quickly
- ) single layer of surface cell
- ) good blood supply to assist quick absorption
Besides active transport going against the concentration gradient what is another difference between it and diffusion?
It requires energy
How do particles move during active transport?
Against the concentration gradient, from a lower to a higher concentration
How are root hairs specialised for absorbing water and minerals?
The cells on the surface of the root grow into long hairs giving them a bigger surface area increasing the rate of absorption
Do root hairs use diffusion, osmosis or active transport?
Active transport
Why does active transport happens on root hairs?
The concentration of minerals is usually higher on the root hair cells than in the soil around it, so diffusion can’t happen if the root hair cell are to take up nutrients, this is why active transport happens as it works against the concentration gradient
What is active transport essential for in plants?
Growth
Where does active transport take place in humans?
In taking nutrients from the gut into the blood
Why does active transport and diffusion have to take place in the gut?
When there’s a higher concentration of glucose and amino acids in the gut they diffuse naturally into the blood however when there is a lower concentration of nutrients in the gut it means that the concentration gradient is the wrong way and so active transport has to be used to continually absorbs nutrients
What does active transport allow the gut to do?
All nutrients to be taken into the blood even when the concentration gradients is the wrong way
What are the names of the two vessels that transport stuff around plants?
Xylem and phloem
What do the phloem and xylem transport?
Phloem transports food substances (mainly dissolved sugars), and the xylem tube carries water and minerals up the plant
Which directions do the xylem and phloem transport stuff?
Phloem - both ways
Xylem - upwards only
What is the phloem made off?
Living cells with small holes in the end to allow stuff to flow through
What is the xylem made of?
Made of dead cells joined end to end with no end walls between them and a hole down the middle
What is transpiration in plants?
The loss of water from the plant
What is transpiration caused by?
Evaporation and diffusion of water from inside the leaves
What does transpiration stream mean?
As water is lost through transpiration more water is drawn from the roots creating the constant transpiration stream
What is the circulatory systems function?
To get food and oxygen to every cell in the body and to carry waste products like carbon dioxide and urea to where they can be removed
Do we have a single or double circulatory system?
Double
What are the two different circulatory systems?
The first one pumps deoxygenated blood to the lungs to take in oxygen and the returns it to the heart, the second one pumps oxygenated blood around all the other organs of the body, when the blood gives up its oxygen at the body cells the deoxygenated blood is returned to the heart.
What in the heart makes sure the blood goes in the right direction?
The valves prevent blood from flowing backwards
What are the four chambers in the heart?
Right atrium, right ventricle, left atrium and left ventricle
How does blood pump around the heart?
Blood flows into the two atriums through the vena cava and the pulmonary vein
The atrium contact pushing the blood through the value and into the ventricles
The ventricles contract forcing the blood into the pulmonary artery and the aorta and out of the heart
The blood them flows to the organs through the arteries and returns through the veins
The cycle starts again
What is the name of the main artery and vein in the right side of the heart?
Artery - pulmonary artery
Vein - vena cava
What is the name of the main artery and vein in the left side of the heart?
Vein - pulmonary vein
Artery - aorta
What is the name of the two main arteries in the heart?
Pulmonary artery and the aorta
What is the name of the two main veins in the heart?
Vena cava and the pulmonary vein
Do vein transport blood away from the heart?
To into the heart
What transports blood away from the heart?
Arteries