B2 Topic 3

Front 1

what us a fossil?

Back 1

any trace of an organism that lived a long time ago

Front 2

what are 3 ways that fossils are formed?

Back 2

1. gradual mineral replacement
2. casts and impressions
3. preservation in places where no decay occurs

Front 3

how does gradual mineral replacement allow organism to fossilise?

Back 3

things like teeth, shells and bones don't decay very quickly at all so they last a long time once buried. Overtime, the material is replaced by minerals and forms a rock like substance which remains the same distinct shape as the organism in the ground

Front 4

how do casts and impressions allow organism to fossilise?

Back 4

when an organism in buried in soft material (clay), it will make an impression in the ground and when the material hardens around the decaying organism, it leaves a cast shape in the ground.

Front 5

how does preservation in places where no decay occurs allow organism to fossilise?

Back 5

when the conditions aren't suitable for microbes to work, the organisms cannot decay, so it is preserved in the ground. e.g. glaciers (too cold), peatbogs (too acidic) and amber (no oxygen/moisture)

Front 6

what 3 things do fossil layers show us?

Back 6

1. what organisms looked like
2. how long ago they existed
3. how they evolved

Front 7

how do fossil layers indicate the age of the organism?

Back 7

generally, the further underground, the older the fossil is.

Front 8

how do fossil layers provide evidence for evolution?

Back 8

we can see how species have evolved and changed over billions of years by looking at the placement of fossils underground e.g. fossilised bones of the horse with changing forefeet

Front 9

the fossil record is...

Back 9

...incomplete

Front 10

why is it incomplete?

Back 10

1.very few organisms can actually fossilise - most decay
2. some body parts (soft tissue) tend to decay away completely
3. we have not discovered all the fossils

Front 11

what is a pentadactyl limb?

Back 11

a limb with 5 digits

Front 12

where is the pentadactyl limb found?

Back 12

in many animals e.g. mammals, reptiles, amphibians

Front 13

what makes species with the pentadactyl limb similar and what makes them different?

Back 13

they have similar bone structures but different funtions

Front 14

give an example

Back 14

the human hand and bat wings are very similar in structure but we don't use our hands to fly

Front 15

how is the pentadactyl limb evidence for evolution?

Back 15

species with this limb are likely to have all evolved from a common ancestor because otherwise, it would be highly unlikely that we all share such a similar bone structure

Front 16

what is growth?

Back 16

an increase in size or mass

Front 17

what are three things you can measure to identify growth?

Back 17

1.size
2.wet mass
3.dry mass

Front 18

what are size measurements?

Back 18

height, length, width, circumference

Front 19

what is a wet mass measurements?

Back 19

it is the mass of an organism including all the water in its body

Front 20

what is the risk with this?

Back 20

it can vary a lot from day to day

Front 21

what is a dry mass measurement?

Back 21

the mass of an organism with no water in its body

Front 22

what is the disadvantage of this?

Back 22

It can only be done once the organism is dead and dried out

Front 23

what three processes cause organism to grow and develop?

Back 23

1.cell differentiation
2.cell division
3.cell elongation

Front 24

what is cell differentiation?

Back 24

the process in which cells change and specialise for a specific job

Front 25

what is cell division?

Back 25

when cells divide and multiply through mitosis

Front 26

what is cell elongation?

Back 26

it only happens in plants. The cell expands, thereby making the cell bigger and making the plant grow

Front 27

true or false:
plants and animals grow in the same way

Back 27

false

Front 28

growth in animals happens through...

Back 28

...cell division

Front 29

animals tend to grow when...

Back 29

....they are young

Front 30

when they reach full growth...

Back 30

...they stop growing

Front 31

describe the rate of cell division/differentiation over a person's life

Back 31

when they are young, their cells rapidly divide and cause them to grow, but over time their cell division slows down and is mostly for repair. In addition, cell differentiation is lost at a young age

Front 32

plants often grow....

Back 32

...continuously

Front 33

describe growth in plants

Back 33

continue to develop new parts and therefore, differentiation occurs continuously. Growth in height is mostly due to cell elongation.

Front 34

where does cell division mostly occur in plants?

Back 34

in root tips and shoot tips

Front 35

what do specialised cells form?

Back 35

form tissues

Front 36

what do tissues form?

Back 36

organs

Front 37

what do organs form?

Back 37

organ systems

Front 38

what is a tissue?

Back 38

a group of similar cells that work together to carry out a certain function

Front 39

what is an organ?

Back 39

a group of different tissues that work together to carry out a certain function

Front 40

what is an organ system?

Back 40

a group of organs that work together to carry out a certain function

Front 41

what organ system is the heart part of?

Back 41

the circulatory system

Front 42

describe the route of blood from the lungs

Back 42

lungs ---> (oxygenated blood) ---> pulmonary vein ---> left atrium ---> left ventricle ---> aorta ---> body ---> (deoxygenated blood) ---> vena cava ---> right atrium ---> right ventricle ---> pulmonary artery ---> lungs

Front 43

which chamber has the thickest muscle and why?

Back 43

the left ventricle because it pumps the blood around the whole body, as opposed to just pumping it to the lungs

Front 44

what is the function of the valves?

Back 44

to prevent the back flow of blood

Front 45

what is the function of red blood cells?

Back 45

to carry oxygen from the lungs to the rest of the body

Front 46

how are they adapted to their function? 2 things

Back 46

- bioconcave disc to give large surface area for absorbing oxygen
- don't have a nucleus to allow more room for haemoglobin

Front 47

what is haemoglobin?

Back 47

substance which contains lots of iron and combines with the oxygen to carry it around the body to different cells

Front 48

what is formed when oxygen and haemoglobin combine?

Back 48

oxyhaemoglobin

Front 49

what happens to the oxyhaemoglobin in body cells?

Back 49

they separate to give the oxygen to the cells and haemoglobin remains in the red blood cell

Front 50

what happens if your body has a lack of iron?

Back 50

can lead to a type of anaemia and the blood can't carry enough oxygen

Front 51

what is the function of white blood cells?

Back 51

to defend against disease

Front 52

what are 3 things that white blood cells can do?

Back 52

1. change shape to remove unwelcome microorganisms
2. release antibodies to fight microorganisms
3. produce antitoxins to neutralise toxins produced by microorganisms

Front 53

what would a low white blood cell count indicate?

Back 53

an increase in the risk of infection

Front 54

what would a high white blood cell indicate?

Back 54

an infection is present or even leukaemia

Front 55

what is the function of platelets?

Back 55

help blood clot

Front 56

what is a platelet?

Back 56

a small fragment of a cell

Front 57

why do they clot blood?

Back 57

to help clot a wound and stop blood from pouring out and stop microorganisms getting in

Front 58

what would a lack of platelets cause?

Back 58

excessive bleeding and bruising

Front 59

what is the function of plasma?

Back 59

to carry everything in blood

Front 60

describe plasma

Back 60

pale yellow liquid

Front 61

what does it carry?

Back 61

red blood cells, white blood cells, platelets, amino acids, glucose, water, carbon dioxide, urea, hormones, antibodies and antitoxins

Front 62

what is urea?

Back 62

waste product from the liver

Front 63

where does plasma take urea?

Back 63

to the kidneys

Front 64

where does plasma take hormones to and from?

Back 64

glands to target organ

Front 65

what transports blood around the body?

Back 65

blood vessels

Front 66

what type of blood vessel takes blood away from the heart?

Back 66

arteries

Front 67

what type of blood vessel takes blood to the heart?

Back 67

veins

Front 68

what type of blood vessel is involved in the exchange of material with cells?

Back 68

capillaries

Front 69

how are arteries adapted to do their job?

Back 69

they carry blood under high pressure: strong and elastic walls with a relatively thick muscle wall compared to the lumen

Front 70

how are veins adapted to do their job?

Back 70

they carry blood under low pressure: less thick walls and bigger lumen to all blood to flow still

Front 71

how are capillaries adapted to do their job?

Back 71

exchange with cells: really small, one cell thick permeable walls to be efficient in exchange. Carry blood very close to every cell

Front 72

arteries branch out into...

Back 72

...capillaries

Front 73

capillaries join up into...

Back 73

...veins

Front 74

where are valves found? why?

Back 74

in veins because blood is under low pressure so there is more chance of backflow

Front 75

starch, proteins and fats are _____ molecules

Back 75

big

Front 76

what does this mean when is comes to digestion?

Back 76

they cannot pass through the digestive system's walls

Front 77

what are 4 smaller molecules that starch, fats and proteins are broken down into?

Back 77

amino acids, sugars, glycerol and fatty acids

Front 78

what breaks down the big molecules?

Back 78

digestive enzymes

Front 79

true or false:
big and small molecules are soluble

Back 79

false
only small molecules are soluble

Front 80

what a the three types of digestive enzymes?

Back 80

carbohydrases
proteases
lipase

Front 81

gives an example of a carbonhydrase

Back 81

amylase

Front 82

give an example of a protease

Back 82

pepsin

Front 83

what do carbohydrases do?

Back 83

digest starches into sugars

Front 84

what do proteases do?

Back 84

digest proteins into amino acids

Front 85

what does lipase do?

Back 85

digests fats into fatty acids and glycerol

Front 86

digestive enzymes are produced...

Back 86

..in various places in the digestive system

Front 87

what is the route for food through the digestive system?

Back 87

mouth ----> oesophagus ----> stomach ----> (liver) ----> (gall bladder) -----> (pancreas) ----> small intestine ----> large intestine

Front 88

what occurs in the mouth?

Back 88

-food is chewed into bolus
-salivary glands produce saliva to moisten food
-salivary glands produce amylase to digest starch

Front 89

what does the oesophagus do?

Back 89

-peristalsis pushes food down the tube
-takes food from mouth to stomach

Front 90

what occurs in the stomach?

Back 90

-food is pummelled by muscular walls
-produces pepsin
-HCl acid provides right environment for pepsin to break down proteins (pH2)
-HCl kills bacteria
-

Front 91

what occurs in the liver?

Back 91

-bile is produced here

Front 92

what does bile do?

Back 92

-neutralises stomach acid
-emulsifies fats

Front 93

what occurs in the gall bladder?

Back 93

-bile is stored here
-bile is released into small intestine

Front 94

what occurs in the pancreas?

Back 94

-produces proteases, lipase and carbohydrases
-releases enzymes into small intestine

Front 95

what occurs in the small intestine?

Back 95

-produces lipase, proteases and carbohydrases to complete digestion
-'food' is absorbed into the blood

Front 96

what occurs in the large intestine?

Back 96

excess water is absorbed from the food

Front 97

what three features in the digestive system are specialised?

Back 97

peristalsis
villi
bile

Front 98

what are the two types of muscle?

Back 98

longitudinal and circular

Front 99

describe longitudinal muscles

Back 99

they run down the length of the gut

Front 100

describe circular muscles

Back 100

they run is circles around the gut

Front 101

what is the job of these muscles?

Back 101

to squeeze food along - peristalsis

Front 102

waves of circular muscle contractions...

Back 102

...push the food along the gut

Front 103

waves of longitudinal muscle contractions...

Back 103

...run slightly ahead to keep the food in a ball

Front 104

what is the function of bile?

Back 104

-neutralise stomach acid
-emulsify fats

Front 105

why does it neutralise stomach acid?

Back 105

stomach acid (HCl) is too acidic for enzymes in the small intestine to work. So, bile which is alkaline, neutralises the acid in the small intestine so that the enzymes can work there

Front 106

why does is emulsify fats?

Back 106

emulsifying fats is breaking fat into smaller droplets giving it a larger surface area for the lipase to digest it - quicker digestion

Front 107

what is villi and where can it be found?

Back 107

they are tiny little projections found on the inside surface of the small intestine

Front 108

what 3 features of villi make absorbing digested food into the bloodstream especially efficient?

Back 108

1. give a larger surface area - quicker absorption
2. single layer of cells - quicker diffusion
3. capillary network supplies them with a good supply of blood - quicker absorption

Front 109

what is a functional food?

Back 109

a food that has a health benefit beyond normal nutrition

Front 110

what are three functional foods?

Back 110

probiotics, prebiotics, plant stanol esters

Front 111

what are probiotics?

Back 111

they contain 'good' live bacteria which are similar to bacteria that is naturally occurring in the gut

Front 112

give two examples of the type of bacteria found in probiotics

Back 112

BIFIDObacteria and LACTObacillus

Front 113

what foods are probiotics found in?

Back 113

yogurt, soya milk and dietary supplements - either naturally occurring or added by manufacturer

Front 114

how are they supposed to help?

Back 114

thought to keep digestive system healthy and keep immune system strong

Front 115

what are prebiotics?

Back 115

carbohydrates that we can't digest

Front 116

where do they naturally occur?

Back 116

in leeks, onions and oats

Front 117

is there enough in these foods to have a significant effect?

Back 117

no, many people take supplements which contain prebiotics

Front 118

what do prebiotics do?

Back 118

they are a food supply for 'good' bacteria in the gut. It is thought that it promotes the growth of good bacteria which in turn strengthens immune system and a more healthy digestive system

Front 119

what are plant stanol esters and what do they do?

Back 119

they are chemicals which lower blood cholesterol and thereby reduce the risk of heart disease

Front 120

where are they found?

Back 120

occur naturally in small quantities in plants but also produced commercially and added to things like spreads

Front 121

how are they produced commercially?

Back 121

by using bacteria to convert sterols into stanols