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Flashcards in Biology topic 1 Deck (44)
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1

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.

2

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.

3

What is a dipolar molecule?

A molecule with two charges, one slightly positive end and one slightly negative end.

4

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.

5

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.

6

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.

7

What is the structure of an artery?

.Thick muscle and elastic tissue- cope with high pressure
.Inner endothelium is folded- allowing expansion

8

What is the function of an artery?

Carries oxygenated blood from the heart to the body.

9

What is the structure of a vein?

.Wide
.Less elastic and muscle tissue- low blood pressure
.Valves- prevent backflow

10

What is the function of a vein?

Takes deoxygenated blood back to the heart

11

What is the structure of a capillary?

.Small
.Endothelium is one cell thick- speeds up diffusion

12

What is the function of a capillary?

Where metabolic exchange occurs

13

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.

14

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)

15

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.

16

Describe the practical that investigates heart rate?

1.Make five caffeine solutions of different concentrations including a control of no concentration.
2.Transfer one daphnia onto a cavity slide
3.Using a pipette, place a few drops of caffeine solution onto the daphnia
4.Place the slide of daphnia onto the stage of a light microscope, adjust the focus so that the heart is visible
5.Count the number of heartbeats in 20 seconds, using a stopwatch and multiply it by three to calculate beats per minute
6.Repeat this with the other caffeine solutions using different daphnia and calculate the beats per minute
7.Compare the results

17

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.

18

How do atheromas form?

.Damage occurs to the artery wall
.Inflammatory response- white blood cells move to the area
.White blood cells and lipids form fatty streaks
.Over time more white blood cells, lipids and connective tissues build up to form a fibrous plaque (atheroma)
.The plaque partially blocks the lumen of the artery and restricts blood flow which causes blood pressure to increase
.The hardening of the arteries is called atherosclerosis

19

How are blood clots formed?

.A protein called thromboplastin is released from the damaged blood vessel
.Thromboplastin and calcium ions triggers the conversion of a soluble protein- prothrombin into an enzyme- thrombin
.Thrombin catalyses the conversion of fibrinogen- a soluble protein into fibrin- solid insoluble fibres
.The fibrin fibres tangle together and form a mesh where platelets and red blood cells get trapped- a blood clot

20

How can blood clots cause cardiovascular disease?

g

21

What are the factors that increase the risk of cardiovascular diseas?g

h

22

What is conflicting evidence

h

23

What is the difference between correlation and causation?

hh

24

Evaluate the design of studies used to determine health risk factors

h

25

Why do people overestimate the risk

hh

26

Why do people underestimate the risk

h

27

How do anticoagulants help to decrease the risk of CVD?

h

28

How do antihypertensives reduce the risk of CVD

h

29

How do statins reduce the risk of CVD

h

30

How do platelet inhibitors reduce the risk of CVD

h

31

What are the benefits of anticoagulants?

h

32

What are the benefits of antihypertensives?

h

33

What are the benefits of statins?

hh

34

What are the benefits of platelet inhibitors?

h

35

How is water important?

Water is a polar solvent and can be used to transport biological molecules.

36

Define dipolar molecule

When the molecule has two charges, slightly positive end and a slightly negative end.

37

How is a water molecule polar?

Due to uneven distribution of charge within the molecule – the hydrogen atoms have a partial positive charge and the oxygen atom has a partial negative charge due to the difference in electronegativity, causing one end of the molecule to be more positive than the other.

38

What is the structure of an artery?

.Small lumen to maintain high blood pressure
.Endothelium (protects against damage, and provides a smooth surface .Thick layer of smooth muscle (contract and relax to dilate and constrict
blood vessels) and elastic fibres (stretch and recoil)
.Collagen fibres (for strength and support)

39

What is the function of an artery?

Carry oxygenated blood to the body tissues

40

What is the function of a vein?

Carry deoxygenated blood to the lungs

41

What is the structure of a vein?

.Large lumen
.Endothelium
.Thin layer of muscle and elastic fibres
.Collagen fibres
.Valves (to prevent backflow)

42

What is the structure of the capillary?

.Lumen
.Endothelium-one cell thick

43

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44

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