Biology 3a Summary Questions Flashcards
A solution of pure water is separated from a concentrated sugar solution by a partially permeable membrane. In which direction will molecules flow, and what substance will these molecules be?
The molecules will flow from the high concentration of water (dilute) to the concentrated sugar solution by osmosis. They will be water molecules.
What are the main substances that diffuse out of leaves?
Oxygen and carbon dioxide.
What conditions does evaporation of water from leaves happen most quickly in?
1) breezy
2) hot
3) dry
How is the alveoli’s structure ideal for gas exchange?
1) large surface area for lots of gas exchange
2) thin walls for short diffusion distance
3) good blood supply for lots of gas exchange from the blood
4) moist lining
How does the structure of a villus mean it is good at its job?
1) single layer of surface cells
2) good blood for fast absorption
Give the two main differences between active transport and diffusion.
1) active transport is against the concentration gradient (low to high concentration) whereas diffusion is high to low concentration
2) active transport requires energy whereas diffusion doesn’t
Describe the role of:
a) the phloem
b) the xylem
a) to transport food to growing regions and storage organs of the plant
b) to transport water to the stem and leaves in the transpiration system
Give the functions of the following parts of the heart:
a) atria
b) ventricles
c) valves
a) contract to pump blood into the ventricles
b) contract to force blood into the pulmonary artery and the aorta (out of the heart)
c) to make sure the blood flows in the correct direction (doesn’t go back on itself)
Why do arteries need very muscular, elastic walls?
They carry blood under high pressure so need to be able to bend and go back to their original shape is squashed.
How are capillaries adapted to their function?
1) permeable walls for diffusion
2) one cell thick so shorter diffusion distance so more diffusion occurs
3) tiny so can get near cells
What’s the substance is red blood cells called and what is it called when it combines with oxygen?
Haemoglobin and when it combines with oxygen it is called oxyhaemoglobin.
What are the cell fragments called that help clot blood and why are they important?
Platelets help clot blood at a wound or bruise to stop excessive bleeding (which leads to blood loss of internal bleeding).
Define homeostasis.
The maintenance of a constant internal environment.
What does the body need to keep fairly constant?
1) temperature
2) sugar content
3) water content
4) ion content
What are three things the body can do if it gets too cold?
1) shivering requires respiration which releases energy, which keeps the body warmer
2) blood vessels near the skin contract to stop blood supply to the skin
3) hairs stand on end to make a larger surface area and to trap warm air close to the skin
