Biology Flashcards
How do dissolved substances move
Through diffusion and active transport
How does water move across borders
Osmosis
What is osmosis
Diffusion of water from a dilute to more concentrated solution through a partially permeable membrane that allows the passage of water molecules
What causes water to move in and out of the cells by osmosis
Difference in concentration inside and outside the cell
What do most soft drinks contain
Water
Sugar
Ions
Why do sports drinks contain sugar
To replace the sugar used in energy release during the activity
Why do sports drinks contain water and ions
To replace the water and ions lost through sweat
What happens if water and ions are not replaced
The ion/water balance is disturbed and the cells do not work as efficiently
What is active transport
When substances are absorbed against a concentration gradient using the energy from respiration
Many organisms are specialised for exchanging materials. How can the effectiveness of an exchange surface increase
Having a large surface area
Being thin - to create a short diffusion path
Having an efficient blood supply (in animals)
Being ventilated (in animals, for gaseous exchange)
Why are gas and solute exchange surfaces in humans and other organisms adapted
To maximise effectiveness
The size and complexity increases …
… The difficulty of exchanging materials
The surface area of the lungs are increased by…
… Alveoli
The surface area of the small intestine is increased by…
… Villi
How do villi absorb the products of digestion
By diffusion and active transport
What are the adaptations of villi
Large surface area
Extensive network of capillaries for absorption
Where are the lungs
In the upper part of the body (thorax)
Protected by the ribcage
Separated from the lower part of the body (abdomen) by the diaphragm
Why does the breathing system take air into and out of our system
So that oxygen can be diffused into the bloodstream
So that carbon dioxide can be diffused from the bloodstream into the air
How does air move into the lungs
The ribcage moves down and out
The diaphragm become flatter
What is ventilation
The movement of air in and out of the lungs
What do the roots absorb
Water and mineral ions
How does carbon dioxide enter plants
Through leaves
How is the surface area of leaves increased
It’s flattened shape and internal air spaces
What do stomata do
Obtain carbon dioxide from the atmosphere
Remove oxygen through respiration
Where is the main water loss in plants
In the stomata, in the leaves
When is evaporation faster
In hot, dry or windy conditions
How can the stomata help with excessive water loss
Close to prevent wilting as water is being lost faster than replaced by the roots
How is the size of stomata controlled
Guard cells that surround them
What does the circulatory system do
Transport substances around the body
What is the heart
An organ, mostly made up of muscle tissue that pumps blood around the body
What are the main chambers in the heart
Left atrium
Left ventricle
Right atrium
Right ventricle
Properties of arteries
Thick walls compared to the lumen
Thick layers of muscle to make them strong
Elastic fibres to allow them to stretch and bounce back
These carry blood away from the heart
Properties of veins
Thinner walls and often have valves to prevent back-flow of blood
These carry blood to the heart
When are stents used
When the arteries begin to narrow and restrict blood flow
What are capillaries
Thin-walled blood vessels that are involved in the exchange of materials at the tissues
Have permeable walls so substances can diffuse
Supply food and oxygen and take away CO2
Substances needed by the cell in body tissues pass …
…out of the blood
Substances produced in the cells pass …
… Into the blood, through the capillary walls
What is blood
A tissue
What does blood consist of
A fluid called plasma in which red blood cells, white blood cells and platelets are suspended
What does blood plasma transport
Carbon dioxide from the organs to the lungs
Soluble products of digestion from the small intestine to other organs
Urea from the liver to the kidneys
Hormones
Antibodies and antitoxins produced by white blood cells
What do red blood cells transport
Oxygen from the lungs to the organs
In the lungs, oxygen and haemoglobin come together to make
Oxyhaemoglobin
Where does oxyhaemoglobin split up
Organs (excluding the lungs) into oxygen and haemoglobin
What are white blood cells part of
The body’s defence system against microorganisms
What are platelets
Small fragments of cells
What do platelets help with
Blood to clot at the site of the wound
What are the separate transport systems in flowering plants
Xylem tissue
Transpiration stream
Phloem tissue
Xylem tissue
Transports water and mineral ions from the roots to the stem and leaves
Phloem
Carries dissolved sugars from the leaves to the rest of the plant, including the growing regions and storage organs
Waste products that have to be removed
Carbon dioxide
Urea
How is carbon dioxide produced and removed
Respiration
Via the lungs when we breathe out
How is urea produced and removed
In the liver by the breakdown of amino acids
In the kidneys, in urine which is temporarily stored in the bladder
What happens if the water and ion content is wrong
Too much water may move in and out of the cell and damage it
How do water and ions enter the body
When we eat and drink
How does a healthy kidney produce urine
Filtering the blood
Reabsorbing all the sugar
Reabsorbing the dissolved ions needed by the body
Reabsorbing as much water as the body needs
Releasing urea, excess ions and water as urine
How are people who suffer from kidney failure treated
Using a kidney dialysis machine
Having a healthy kidney transplanted
What does treatment by dialysis restore
The concentration of dissolved substances in the blood and has to be carried out at regular intervals
In a dialysis machine, a person’s blood flows through a …
… Partially permeable membrane
The dialysis fluid contains the same concentration of …
… Of useful substances in the blood. This ensures that glucose and mineral ions aren’t lost
What passes out of the blood and into the dialysis fluid
Urea
What happens in a kidney transplant
A diseased kidney is replaced with a healthy one by a donor