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IGCSE Biology > Topic 3 > Flashcards

Topic 3 Flashcards

no diagrams. no fibrinogen

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1
Q

What does the mouth and salivary glands do?

A

The teeth grind food into small pieces. Salivary glands release saliva, containing amylase (enzymes) which breaks starch into maltose, then broken down by maltase into glucose.

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2
Q

What does the oesophagus do?

A

At the back of the mouth, the food is made into a ball called the bolus. The bolus is pushed down the oesophagus by rings of muscle, by a motion called peristalsis.

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3
Q

What does the stomach do?

A

Main organ where food is digested. Muscles churn the food. Enzymes (e.g. pepsin) are added along with hydrochloric acid

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4
Q

What does the small intestine do?

A

Absorbs nutrients and most water. It is made from microscopic villi that increases the surface area so more nutrients can be absorbed quicker.

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5
Q

What does capillaries do?

A

Blood flow maintains concentration gradient (quicker diffusion)

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6
Q

Where is the ileum and what does it do?

A

The last part of the small intestine, where most of the nutrients is absorbed.

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6
Q

What is the duodenem?

A

Part of the small intestine. Food enters the duodenem where bile and further digestive enzymes are added to further digest food.

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7
Q

What does the large intestine do?

A

Mainly indigestible food and water enter here. Absorbs water back into the bod

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8
Q

What does the liver & gallbladder do?

A

Liver produces bile which helps digest lipids. The gallbladder stores the bile until it is ready to be released into the small intestine.

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9
Q

What does the pancreas do?

A

Produces enzymes involved in digestion. Also produces insulin and glucagon (regulate blood sugar levels)

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10
Q

Define ingestion:

A

The taking of substances into the body.

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11
Q

Define digestion:

A

The breakdown of food.

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12
Q

Define absorption:

A

The movement of nutrients from the intestines into the blood.

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13
Q

Define assimilation:

A

The uptake and use of nutrients by cells.

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14
Q

Define egestion:

A

The removal of undigested food from the body as faeces.

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15
Q

What is physical digestion?

A

The breakdown of food into smaller pieces without chemical change to the food molecules. Physical digestion increases the surface area of food for the action of enzymes in chemical digestion.

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16
Q

What do canines do?

A

Cut and tear up food.

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17
Q

What do molars do?

A

Teeth that do the most chewing work while eating.

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18
Q

What do incisors do?

A

Work to bring food into the mouth and cut it.

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18
Q

What do premolars do?

A

Helps incisors and canines grind and mix food while chewing.

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18
Q

What does bile do?

A

Helps to emulsify fats, increasing the surface area for faster chemical digestion by enzymes.

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19
Q

What does the stomach do to help physical digestion?

A

Muscular contractions to churn up/break the food.

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20
Q

What are the 3 main types of enzymes?

A
  1. Carbohydrases
  2. Lipases
  3. Proteases
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21
Q

Where is amylase produced and where is it excreted?

A

Produced in the salivary glands and pancreas. Excreted in the mouth and duodenem.

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22
Q

What does amylase (CARBOHYDRASES) do?

A

Amylase breaks down starch into maltose, which is then broken down by maltase into glucose.

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23
Q

Where are lipases (digests lipids) produced and excreted?

A

Produced in the pancreas and secreted in the duodenem.

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24
Q

Where does the breakdown of maltose into glucose occur?

A

In the epithelium membrane of the small intestine.

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25
Q

Where are proteases (digests proteins) produced?

A
  1. Pepsin = found in the stomach and digests protein into amino acids
    2.Trypsin = produced in the pancreas and secreted into the duodenem, also digests proteins to amino acids.
26
Q

What is pepsin optimised for?

A

Acidic conditions (stomach contains hydrochloric acid)

27
Q

What is trypsin optimised for?

A

Slightly alkaline conditions after bile neutralizes the hydrochloric acid in the duodenem.

28
Q

What is the role of hydrochloric acid in the stomach?

A

To kill pathogens/harmful micro-organisms and providing an acidic pH for optimal enzyme activity.

29
Q

What do villi and micro villi do?

A

increase the internal surface area of the lining in the small intestine, resulting in quicker diffusion of nutrients/water into the body.

30
Q

What is the structure of the villus?

A

Small and slender, increases surface area of membrane.

31
Q

What role do capillaries and lacteal play?

A

To maintain a steep concentration gradient (quicker diffusion)

32
Q

What does lacteal do?

A

Absorb fats.

33
Q

What do capillaries in the villus do?

A

Transports water, amino acids, sugars and vitamins.

34
Q

What does xylem do?

A

Transport of water and mineral ions. Also gives support

35
Q

Features of xylem:

A
  • Thick walls (lignin) to withstand pressure
  • No cell contents
36
Q

What does the phloem do?

A

Transport of sucrose and amino acids (soluble products)

37
Q

Pathway of water from the soil?

A

Soil -> Root hair -> Root cortex - > Xylem -> Leaves -> Evaporation

38
Q

Where does gaseous exchange take place in a plant?

A

The stomata.

39
Q

What is transpiration?

A

The loss of water vapour from leaves. Water evaporates from the surfaces of mesophyll cells into the air spaces and diffuse out from the stomata as water vapour. This causes the water concentration in the leaf to decrease. Water moves up the plant by osmosis.

40
Q

How does water move through the xylem?

A

Cohesion of water and adhesion to the walls of the xylem vessels allows water to move up (like a straw)

41
Q

3 Factors affecting transpiration:

A
  1. Temperature
  2. Wind speed
  3. Humidity
42
Q

What happens if more water is evaporated from a plant than can be absrobed from the soil?

A

Plant cells become flaccid, therefore resulting in wilting.

43
Q

What is translocation?

A

Movement of sucrose and amino acids in phloem from sources to sinks.

44
Q

What will some plants do during harsh conditions (e.g winter)?

A

Become dormant by reduced activity, and surviving on their stored starch and other materials (converted to sucrose during spring)

45
Q

Features of phloem cells?

A

Have pores in end walls to allow sap cell. Can transport substances in any direction.

46
Q

What are sources?

A

Where plants release sucrose and amino acids. Sources begin as sinks (rate of photosynthesis increase when they develop into net sources)

47
Q

2 examples of sources

A
  1. Leaves: sucrose synthesized, amino acids can also be produced through metabolic pathways.
  2. Phloem tissue: transports sucrose from sources to sinks.
48
Q

What is a sink?

A

Where plants use/store sucrose and amino acids.

49
Q

4 Sinks:

A
  1. Roots (store/absorb from soil)
  2. Fruits
  3. Seeds
  4. Nectar
50
Q

Factors affecting source/sink dynamics in plants:

A

Seasonal variation, reproductive phases and environmental stimuli.

51
Q

What do veins transport?

A

Deoxygenated blood to the vena cava/heart (right atrium)

52
Q

What is chemical digestion?

A

Breakdown of large insoluble molecules into small soluble molecules.

53
Q

What do arteries transport?

A

Oxygenated blood away from the heart (to body)

54
Q

What do coronary arteries/veins do?

A

Supply oxygen, nutrients and remove CO2 from the heart.

55
Q

Where in the heart are the muscle walls thicker?

A

Ventricles. Left ventricle is thicker due to it needing to be able to push blood around the whole body.

56
Q

5 features or arteries:

A
  1. Carry blood at high pressures away from the heart
  2. Carry oxygenated blood (other than pulmonary artery)
  3. Thick muscular walls containing elastic fibres (recoils after blood passes through)
  4. Narrow lumen (maintains high pressure)
  5. Speed flow is fast
57
Q

6 features of veins:

A
  1. Carry blood at low pressure towards the heart
  2. Carry deoxygenated blood (other than pulmonary vein)
  3. Thin walls
  4. Large lumen (as blood pressure is low)
  5. Contains valves (prevents backflow due to slow speed)
  6. Slow speed
58
Q

5 features of capillaries:

A
  1. Carry blood at low pressure within tissues
  2. Carry both oxygenated/deoxygenated blood (easily diffuse in/out)
  3. Walls are single cell thick
  4. ‘Leaky walls’ (aids exchange of larger molecules)
  5. Speed is slow
59
Q

Components of blood:

A

RBCS, WBS, Platelets and plasma

60
Q
A
60
Q

What percentages is blood made up of?

A

Plasma = 55%
Other = 45%

60
Q

What does plasma do?

A

Important for the transport of carbon dioxide, nutrients, urea, ions, hormones and heat energy.

60
Q

What do WBC’S do?

A

Defend the body against infection and pathogens by carrying out phagocytosis and antibody production.

60
Q

Blood clotting:

A

preventing
blood loss and the entry of pathogens. the conversion
of fibrinogen to fibrin to form a mesh

60
Q

What do platelets do?

A

Involved with helping the blood clot.

IGCSE Biology (10 decks)

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