Ib Biology Hl Year 2 Semester 2 Final Reveiw

Front 1

polarity of water

Back 1

water molecules consist of two hydrogen atoms bonded to an oxygen atom, water molecules have two poles- a positive hydrogen pole and a negative oxygen pole. This feature of a molecule is called polarity

Hint 1

hydrogen atoms have a slight positive charge, oxygen atoms have a slight negative charge

Front 2

What are the four most common chemical elements of life

Back 2

carbon, hydrogen, oxygen, and nitrogen

Front 3

what are the functions of lipids

Back 3

energy storage- in the form of fat in humans and oil in plants

heat insulation- a layer of fat under the skin reduces heat loss

buoyancy-lipids are less dense than water so help animals to float

Hint 3

energy storage, heat insulation, buoyancy

Front 4

What are the subunits of DNA

Back 4

Phosphate group, sugar, and the "base"

Front 5

Building DNA molecules

Back 5

two DNA nucleotides can be linked together by a covalent bond between the sugar of one nucleotide and the phosphate group of the other.

DNA molecules consist of two strands of nucleotide wound together into a double helix, hydrogen bonds link the two strands together

Hint 5

what kind of bond links the antiparallel strands together

Front 6

Taking in food

Back 6

humans take in food through the mouth and the esophagus.

food is absorbed in the small intestine in a process called absorption. Small finger like projections from the wall of the small intestine called villi are specially adapted to absorb food molecules. After food has been absorbed it is assimilated and becomes a part of the tissues of the body.

Front 7

the need for digestion

Back 7

food must be broken down because food that humans eat is not suitable for human tissues.

many molecules in food are too large to be absorbed by the villi in the small intestine.

digestion of large molecules happens naturally at body temperature, but only at a very slow rate. Enzymes are essential to speed up the process

Front 8

salivary amylase

Back 8

Salivary Glands,
Starch,
Maltose,
pH 7

Hint 8

source, substrate, products, optimum pH

Front 9

Pepsin

Back 9

wall of stomach
proteins
small polypeptides
pH1.5

Hint 9

source, substrate, products, optimum pH

Front 10

Pancreatic lipase

Back 10

Pancreas
Triglycerides (fats or oils)
fatty acids and glycerol
pH7

Hint 10

source, substrate, products, optimum pH

Front 11

Functions of the stomach

Back 11

digestion of proteins begins in the stomach, catalysed by pepsin. Bacteria, which could cause food poisoning, are most likely killed by the acid conditions of the stomach. The acidity also provides optimum conditions for pepsin to work.

Front 12

Functions of the intestines

Back 12

enzymes secreted by the wall of the small intestine complete the process of digestion. the end products of digestion are absorbed by the villi protruding from the wall of the small intestine.

the indigestible parts of the food, together with a large volume of water, ass on into the large intestine. Water is absorbed here leaving solid feces which are eventually egested through the anus.

Front 13

relationship between structure of a villus and its function

Back 13

villi increase the surface area over which food is absorbed

an apithelium, consisting of only one thin layer of cells, is all that foods have to pass through to be absorbed

protrusions of the exposed part of the plasma membranes of the epithelium cells increase the surface area for absorption.

protein channels in the microvilli membranes allow rapid absorption of foods by facilitated diffusion and pumps allow rapid absorption by active transport

mitochondria in epithelium cells provide the ATP needed for active transport

blood capillaries inside the villus are very clost to the epithelum so the distance for diffusion of foods is very small

a lacteal (a branch of the lymphatic system) in the centre of the villus carries away fats after absorption

Front 14

Heart Structure

Back 14

the heart is a double pump, with the right side pumping blood to the lungs and the left side pumping blood to all the other organs. the walls of the heart are composed of cardiac muscle. Contraction ofcardiac muscle is myogenic
there are many capillaries in the muscular wall of the heart. the blood running through these capillaries is supplied by the coronary arteries which branch of the aorta, close to the semilunar valve. the blood brought by the coronary arteries brings nutrients. it also brings oxygen for aerobic cell respiration, which provides the energy needed for cardiac muscle contraction

Front 15

myogenic

Back 15

can contract on its own iwthout the stimulation of a nerve cell (muscle)

Front 16

which arteries go to the lungs, to the other organs?

Back 16

pulmonary goes to the lungs, aorta goes to other organs

Front 17

where do the vena cava(s) go?

Back 17

right atrium

Hint 17

they are veins

Front 18

where do the pulmonary veins come from

Back 18

lungs

Front 19

what does the atrio-ventricular valve do?

Back 19

prevent back flow into atria

Front 20

what do the semilunar valves do?

Back 20

allow the ventricles to fill with blood
block the arteries from the ventricles

Front 21

arteries

Back 21

thick outer layer of logitudinal collagen and elastic fibres to avoid bulges and leaks

thick wall to withstand high pressures

thick layers of circular elastic and muscle fibres to help pump the blood after each heart beat

narrow lumen to help maintain pressures

Hint 21

thick outer layer

thick wall

muscles

narrow lumen

Front 22

veins

Back 22

thin layers with a few circular elastic and muscle fibres because blood does not flow in pulses so theveins wall cannot help pump it.

wide lumen is needed to accomodate the slow flowing blood

thin wall allows the vein to be pressed flat by adjacent muscles, helping to move the blood

thin outer layer of logitudinal collagen and elastic fibres because there is littledanger of bursting

Hint 22

thin layers

wide lumen

thin wall

thin outer layer

Front 23

capillaries

Back 23

wall consists of a single layer of thing cells so the distance for diffusion in or out is small

pores between cells in the wall allow some o the plasma to leak out and form tissue fluid. phagocytes can also squeee out

very narrow lumen so that the capillaries can fit into small spaces. many small capilarries have a larger surface area than fewer wider ones

Hint 23

single layer wall

pores between cells

very narrow lumen

Front 24

atria

Back 24

collecting chambers

Front 25

ventricles

Back 25

pumping chambers

Front 26

action of the heart

Back 26

the walls of the atria contract, pushing blood from the atria into the ventricles through the atrioventricular valves, which are open. the semi lunar valves are closed, so the ventricles are filled with blood

the walls of the ventricles contract powerfully and the blood pressure rapidly rises inside them. this rise in pressure first cuases the atrioventricular valves to close, preventing back-flow of blood to the atria and then causes the semilunar valves to open, allowing blood to be pumped into the arteries. at the same tiem the atria start to refill as the collect blood from the veins

the ventricles stop contracting and as pressure falls inside them the semilunar calves close, preventing back-flow of blood from the arteries to the ventricles. when the ventricular pressure drops below the atrial pressure the atrioventricular valves open. Blood entering the atrium from the veins then flows on to start filling the ventricles.

Front 27

what controls the heart beat?

Back 27

pacemaker

Front 28

what can transmit messages to the pacemaker

Back 28

one nerve carries messages from the brain to the pacemaker that tell the pacemaker to speed up the beating of the heart

another nerve carries messages from the brain to the pacemaker that tell the pacemaker to slow down the beating

adrenalin carried to the pacemaker by the bloodstream, tells the pacemaker to speed up the beating of the heart

Front 29

what kind of cells are in blood

Back 29

plasma, erythrocytes, leukocytes and platelets

Front 30

what is an erythrocyte

Back 30

red blood cell

Front 31

what is a leukocyte?

Back 31

white blood cell

Front 32

functions of blood

Back 32

transport and defense against infectious disease

Front 33

what do red blood cells transport

Back 33

oxygen from lungs to respiring cells

Front 34

what does blood plasma transport

Back 34

nutrients

carbon dioxide

hormones

antibodies

urea

Front 35

what are antibodies

Back 35

antibodies are proteins that recognize and bind to specific antigens

Front 36

what are antigens

Back 36

antigens are foreign substances that stimulate the production of antibodies

Front 37

what is the main function of antibodies

Back 37

to defend the body against pathogens by binding to antigens on the surface of a paathogen and stimulating its destruction

Front 38

what are natrual barriers to infection

Back 38

the skin and mucous membranes

Front 39

how does skin function as a barrier to infection

Back 39

the outer layers are tough and form a physical barrier. sebaceous glands in the skin secrete lactic acid and fatty acids, which make the surface of the skin acidic.

Front 40

how do mucous membranes function as barriers to infection

Back 40

they do not form a strong physical barrier, but many bacteria are killed lysozyme, an enzyme in the mucus.

bacteria can also get caught in the sticky mucus and cilia push the mucus and bacteria out

Front 41

where are mucous membranes found

Back 41

nose, trachea, vagina, and urethra

Front 42

what are antibiotics

Back 42

chemicals produced by microorganisms to kill or control the growth of other microorganisms

Front 43

why do antibiotics not work on viruses

Back 43

viruses carry out very few processes themselve. they rely instead on a host cell such as a human cell to carry out the processes for them. it is not possible to block these precesses with an antibiotic without also harming hte human cells.

Front 44

what do phagocytes do?

Back 44

identify and ingest pathogens

Front 45

what is a pathogen

Back 45

an organism or virus that causes disease

Front 46

production of antibodies

Back 46

antibodies are made by lymphocytes, one of the two main types of leukocyte

a lymphocyte can only make one type of antibody so a huge number of different lymphocyte types is needed. Each lymphocyte puts some of the antibody that it can make into its plasma membrane with the antigen-combining site projecting outwards

when a pathogen enters the body, its antigens bind to the antibodies in the plasma membrane of one type of lymphocyte

when antigens bind to the antibodies on the surface of a lymphocyte, this lymphocyte becomes active and divides by mitosis to produce a clone of many identical cells

the clone of cells starts to produce large quantities of the same antibody- the antibody needed to defend the body against the pathogen.

Front 47

cell respiration

Back 47

happens in the cytoplasm and mitochondria of cells and releases energy in the form of ATP for use inside the cell

Front 48

gas exchange

Back 48

swapping of one gas for another. gas exchange happens in the alveoli of human lungs. oxygen diffuses from the air in the alveoli to the blood in the capillaries. carbon dioxide diffuses in the opposite direction.

this can happen because there are concentration gradients of oxygen and carbon dioxide between the air and the blood.

Front 49

ventilation

Back 49

to maintain the concentration gradients the air in the aveoli must be refreshed frequently.

the process of bringing fresh air to the alveoli

Front 50

trachea

Back 50

tube going into the lungs

Front 51

bronchus

Back 51

branches off the trachea

Front 52

bronchioles

Back 52

branches off bronchus

Front 53

diaphram

Back 53

muscle that allows breathing

Front 54

what are the adaptations of the alveolus to gas exchange?

Back 54

the lungs contain hundreds of millions of alveoli in total, which gives huge surface area for gas exchange

the wall of the alveolus consist of a single layer of very thin cells. the capillary wall also is a single layer of thin cells so the gas only has to diffuse a short distance

alveolus covered by a dense network of blood capillaries

cells in the alveolus wall secrete a fluid which keeps the inner surface of the alveolus moist, allowing the gases to dissolve. The fluid also contains a natural detergent, which precents the sides of the alveoli from sticking together