Biology topic 1 Flashcards
Why do animals have a heart and circulation?
As the size of organisms increase diffusion becomes insufficient. So larger organisms have a mass
transport system, consisting of heart and circulation, which moves the substances around the body and allows exchange of substances to take place.
Why do animals have a heart and circulation?
Most multicellular plants and animals have too small a surface area to volume ratio so diffusion would be too slow to provide the necessary molecules. Therefore, they require a system to transport nutrients and waste products around the organism.
What is a dipolar molecule?
A molecule with two charges, one slightly positive end and one slightly negative end.
Why do multicellular organisms need mass transport systems?
Diffusion is too slow so mass transport systems are used to carry raw materials, remove metabolic waste.
What is the structure of a water molecule?
One atom of oxygen and two atoms of hydrogen. The shared negative hydrogen electrons are pulled towards the oxygen atom making the hydrogens slightly positively charged and the oxygen slightly negatively charged.
Why is water important as a solvent?
Because of water’s dipole nature the slightly positive end of water will attract to the negative ion, and the slightly negative end attracts`to the positive ion so it dissolves the molecule.
What is the structure of an artery?
.Thick muscle and elastic tissue- cope with high pressure
.Inner endothelium is folded- allowing expansion
What is the function of an artery?
Carries oxygenated blood from the heart to the body.
What is the structure of a vein?
.Wide
.Less elastic and muscle tissue- low blood pressure
.Valves- prevent backflow
What is the function of a vein?
Takes deoxygenated blood back to the heart
What is the structure of a capillary?
.Small
.Endothelium is one cell thick- speeds up diffusion
What is the function of a capillary?
Where metabolic exchange occurs
What happens during atriole systole?
The atria contract, which forces the atrioventricular valves open and pushes blood into the ventricles. There is an increased pressure in the ventricles.
What happens during ventricular systole?
The ventricles contract, which pushes the AV valves shut to prevent backflow. There is an increased pressure in the ventricles which forces open the semilunar valves and pushes blood into the arteries ( pulmonary artery, aorta)
What happens during cardiac diastole?
The atria and ventricles relax. The higher pressure in the pulmonary artery and aorta pushes the SL valves closed to prevent backflow.
Describe the practical that investigates heart rate?
- Make five caffeine solutions of different concentrations including a control of no concentration.
- Transfer one daphnia onto a cavity slide
- Using a pipette, place a few drops of caffeine solution onto the daphnia
- Place the slide of daphnia onto the stage of a light microscope, adjust the focus so that the heart is visible
- Count the number of heartbeats in 20 seconds, using a stopwatch and multiply it by three to calculate beats per minute
- Repeat this with the other caffeine solutions using different daphnia and calculate the beats per minute
- Compare the results
Describe the heart
The left ventricle is thicker, has more muscular walls than the right side because it needs to contract powerfully to pump blood all around the body, the right side only pumps blood to the lungs.
The ventricles have thicker walls than the atria because they pump blood out of the heart.
The AV valves link the atria to the ventricles and prevent backflow into the atria.
The SL valves link the ventricles to the pulmonary artery and aorta and prevent backflow into the heart.