chapter 6 - exchange

Question 1

What type of structures will give you a large surface area to volume ratio

Answer 1

Small structures/animals such as mouse and small cubes

Question 2

What type of structures will give you a lower surface area to volume ratio

Answer 2

Larger animals such as polar bears for example

Question 3

Why surface area to volume ratio important

Answer 3

The surface area of a cell is the cell-surface membrane, this is the site of exchange between interior and its exterior external environment. The surface must be big enough to allow sufficient exchange to support the contents (the volume of the cell)

Question 4

Red blood cells and the surface area to volume ratio described

Answer 4

Red blood cells are biconcave discs. The sheep increases the surface area to volume ratio of the cell. This increases the efficiency of diffusion of oxygen and carbon dioxide into and out of the cell. This is an adaptation to increase surface area to volume ratio

Question 5

How surface area to volume ratio limits cell size

Answer 5

A cell is a metabolite were many different reactions occur. The number of reactions increase as the volume of a cell increases. The greater the surface area the larger the amount of raw materials that can enter at any one time. As a cell grows the surface area to volume ratio decreases, at some point in its growth it’s SA/V Ratio become so small that its surface area is too small to supply its raw materials to its volume at this point the cell cannot get larger.

Question 6

Heat loss with surface area to volume ratio

Answer 6

Endothermic animals in colder environments are generally larger. The larger the animal the smaller the surface area to volume ratio therefore there is less of an area to lose heat from.

Question 7

What is an amoeba cell

Answer 7

An amoeba cell is a single celled organism. It has a large surface area to volume ratio therefore it can accomplish the exchange it needs by simple diffusion across its body surface

Question 8

What is ficks law

Answer 8

rate of diffusion = SA X concentration
distance

Rate of diffusion equals surface area times concentration difference divided by distance

Question 9

What is an Insects gas exchange system

Answer 9

The tracheal system - all insects or Aerobic organisms, They obtain oxygen from their environment in order to respire and survive. The tracheal system delivers oxygen to every cell in the body.

Question 10

What are spiracles for insects

Answer 10

Spiracles-are openings on either side of the abdomen through which oxygen and carbon dioxide can enter and leave the body by diffusion.

Question 11

What are valves in the tracheal system for insects

Answer 11

valves- used to open and close the spiracles

Question 12

What are trachea in the tracheal system for insects

Answer 12

trachea- They are a network of large tubes held open by rings of chitin through which air passes

Question 13

What are tracheoles in the tracheal system of insects

Answer 13

tracheoles are smaller branches tubes with no chitin that air passes along. they end in the middle of the insect

Question 14

What are air sacks in the tracheal system of an insect

Answer 14

They are due to muscle contraction, to pump air in and out of the trecheal system in very active insects

Question 15

Describe the tracheal system

Answer 15

Air enters the insect body through the spiracles which are controlled by the valves. Oxygen defuses down a concentration gradient through the trachea. Then oxygen will diffuse down the branched tracheoles. loooooo at the end of the branched tracheole there is a thin moist interface for the exchange of gasses between air and the living cell. oxygen diffuses into the liquid of the tracheole interface then diffuses into the cytoplasm of the adjacent cell. at the same time carbon dioxide (waste product) diffuses out of the cell and eventually out the tracheal system down a concentration gradient.

Question 16

Why does the tracheal system limit the size of insects

Answer 16

The tracheal System is very efficient but For it to be effective the diffusion pathway must be short as diffusion is not a fast process. This then limit the size that insects can be

Question 17

What are the gas exchange organs for fish

Answer 17

The gills

Question 18

describe the structure of a gill

Answer 18

a gill Is located between the BUCCAL cavity and the OPERCULUM cavity. They are composed of many filaments that are each covered in many lamellae.

Question 19

What is an adaptation of a filament

Answer 19

Each filament is covered in many lamellae. Giving a large surface area for gas exchange

Another adaptation is that each filament is thin (one cell thick) Ensuring that there is a short diffusion distance between the blood in the lamellae and the water

Question 20

What would occur if the movement of water was parallel to the movement of blood

Answer 20

This would not provide a favourable concentration gradient as the exchange reaches equilibrium and therefore a concentration gradient isn’t maintained all the way down the Lamelle

Question 21

What is the counter current flow system in fish

Answer 21

The counter current flow gas exchange system in fish ensures that the most oxygen rich water comes in contact with the most oxygen rich blood therefore the most oxygen poor water comes in contact with the most oxygen poor blood. Blood and water flow in opposite Directions to each other. There is always a concentration gradient for oxygen to diffuse into the blood. This is maintained for the whole length of the
lamellae To achieve maximum saturation of the blood. Carbon dioxide defuses out of the blood and into the water down its concentration gradient at the exact same time.

Question 22

What do highly active fish do to ensure they are provided with sufficient oxygen in their blood

Answer 22

They swim with their mouths open, to maintain a high water flow across the gills to provide sufficient oxygen to their blood for high rate of respiration.

Question 23

What are some adaptations for xerophytes (cactus/desert plants)

Answer 23

leaves are reduced to spines/ needles to prevent water loss by evaporation and help to shade the plant. mentains a small surface area to volume ratio to reduce water loss

Shallow roots that cover a lot of surface area of the soil therefore this maximises the diffusion of water into the plant. And roots also penetrate deep into the soil to maximise water diffusion from the water table.

Question 24

Explain the process of gas exchange in plants

Answer 24

Gases into the leaf through the stomata which are controlled by the guard cells. Then the gases diffuse into the air spaces in the leaf which are in direct contact with the spongy Palaside mesophyll cells / cells within the leaf.

Question 25

Why do plants not need a ventilation system

Answer 25

Because their leaves are exposed therefore the air surrounding them is constantly being replaced

Question 26

What happens during photosynthesis to gas exchange

Answer 26

During photosynthesis (daylight hours) this increases the concentration of oxygen in the sub stomatal air spaces. And there is a decrease in carbon dioxide concentration this increases the concentration gradient for these gases increasing diffusion rate.

Question 27

What is the function of the guard cells in gas exchange in plants

Answer 27

Guard cells open and close the pores which controls the rate of gas exchange and water loss

Question 28

The raspatory system gas exchange key features

Answer 28

Trachea-bronchus/bronchi -bronchioles-alveoli

Question 29

What is the structure and function of alveoli

Answer 29

Alveoli are mini air sacs Which are located at the end of the bronchioles, between the alveoli there are collagen and elastic fibres. Which allowed the alveoli to stretch as they filled with air during inspiration. Alveoli have a short diffusion distance for gas exchange

Question 30

What are bronchioles

Answer 30

Bronchioles are a series of branching subdivisions of the bronchi. The walls are made of muscle lined in epithelial cells. Muscle allows them to constrict so they can control the flow of air in and out of the alveoli.

Question 31

What is the structure and function of the Bronchi/bronchus

Answer 31

They are two divisions of the trachea. Each subdivision leads to 1 lung. They also produce mucus to trap dirt and have cilia. Longer bronchi are supported by cartilage

Question 32

What is the structure of the trachea

Answer 32

The trachea is a flexible air way that is supported by rings of cartilage which prevents trachea from collapsing. The back of the trachea is supported by muscle and elastic tissue, the muscle tissue allows the trachea to contract and relax. The elastic tissue allows the trachea to expand/become extended.Cartilage does not surround the whole of the trachea and only supports the trachea in a C shape

Question 33

What is the function of the cilia

Answer 33

Cilia what away mucus from the throat. And it prevents mucus from getting into the lungs.

Mucus secreting cells secrete mucus to protect the mucus membranes and trap the mucus

Question 34

How does oxygen and carbon dioxide defuses from the alveoli to the capillaries vice versa

Answer 34

The alveoli are supported by a network of capillaries over the surface of the alveoli. The alveolar epithelium and the capillary endothelium are very thin to allow efficient rates of diffusion. both gassed flow along a concentration gradient

Question 35

What events occur during inspiration

Answer 35

Inspiration is the act of breathing in

The pressure of the lungs is greater than the pressure of the atmosphere. External intercostal muscles contract while internal intercostal muscles relax. The ribs are pulled upwards and outwards increasing the volume of the throax. The diaphragm muscles contract causing the diaphragm to flatten increasing the volume of the throax. This increased the volume of the throax results in reduction of the pressure of the lungs and air is forced into the lungs

Question 36

What events occurred during expiration

Answer 36

Expiration is the event of breathing out

When the pressure of the lungs is lower than the pressure of the atmosphere. Internal intercostal muscles contract while external intercostal muscles relax. The ribs move downwards and inwards decrease in the volume of the throax. The diaphragm muscles relax causing the diaphragm to be pushed up again, therefore further decreasing the volume of the throax. the decreased volume in the throax increases pressure in the lungs. The pulmonary pressure is now greater than the atmospheric pressure so air is forced out of the lungs

Question 37

Define pulmonary ventilation

Answer 37

Pulmonary ventilation is the total volume of air that is moved into the lungs in one minute

Question 38

Define tidal volume

Answer 38

Tidal volume is the volume of air normally taken in at each breath when the body is at rest.

Question 39

Define ventilation/breathing

Answer 39

The number of breaths taken in one minute this is normally around 12 to 20 breaths

Question 40

what is the equation for pulmonary ventilation rate

Answer 40

Pulmonary ventilation rate = tidal volume(dm3) X breathing/ventilation rate(min-1)

Question 41

What is vital capacity

Answer 41

Vital capacity is the maximum amount of air you can exhale after inhaling.

Question 42

What is residual volume

Answer 42

Residual volume is the volume of air remaining in the lungs after maximum exploration.

Question 43

What is total lung capacity

Answer 43

Total lung capacity is the volume of air in the lungs upon maximum effort of inspiration.

Question 44

What are the essential features of gas exchange surfaces

Answer 44

A large surface area compared with the volume of the organism (millions of alveoli)

A short distance for gas to diffuse (alveoli and capillaries are only one cell thick and cells are flattened)

A large difference in concentration, on opposite sides of the surface due to movement of air and movement of blood to maintain a diffusion gradient

Partially permeable moist surface to allow oxygen and carbon dioxide to diffuse easily

Question 45

Describe how oxygen defuses into the capillaries from the alveoli

Answer 45

Red blood cells are slowed as they pass through the capillaries allowing more time for diffusion to occur. The distance between the alveoli and the red blood cell is reduced as the red blood cells are flattened against the capillaries walls. The walls of both the alveoli and capillaries are very thin allowing for a short diffusion distance. Alveoli and pulmonary capillaries have a large total surface area. Breathing movements constantly ventilate the lungs and the action of the heart circulating blood around the alveoli,Maintaining a steep concentration gradient of the gases. Blood flow through the pulmonary capillaries also maintains a steep concentration gradient.

Question 46

Describe simple diffusion in terms of oxygen diffusing into the blood in the human gas exchange system

Answer 46

Simple diffusion-high concentration to a low concentration,air moves from high partial pressures to low partial pressures. these gases exchanging are often carbon dioxide and oxygen in this example.

Question 47

alveolar air

Answer 47

Alveolar air Is very different from inhaled air, the gas exchange in lungs occurs between alveoli and the red blood cells and capillaries. The volume of blood in the pulmonary capillaries is smaller than the volume of air in the alveoli. The gas exchange process brings partial pressure of oxygen and carbon dioxide in the blood to the same level as in the alveolar air

Question 48

What is the function of the oesophagus

Answer 48

The oesophagus is a tube in the digestive system that carries food to the stomach

Question 49

What is the function of the stomach

Answer 49

The stomach is a muscular sac with an inner layer which produces enzymes. Its role is to store and digest food especially proteins. The stomach has glands that produce enzymes that digests proteins.

Question 50

What is the function of the small intestine/ilium

Answer 50

The small intestine is a long muscular tube, through this further digested by enzymes in the small intestine which are produced in the glands. The inner walls of the small intestine are folded into villi which give them a larger surface area. The surface area increases further increases by microvilli on the epithelial cells of each Villus.

Question 51

what is the function of the large intestine

Answer 51

The large intestine absorbs water, most of the water that is absorbed is water from secretions of the digestive glands

Question 52

What is the function of the rectum

Answer 52

The rectum is the final section of the intestine. faeces is stored here before being removed via the anus. This process is called EGESTION

Question 53

what is the function of the salivary glands

Answer 53

They are situated in the mouth and pass the secretions via a duct. They contain enzymes (amylase) for hydrolysis of starch.

Question 54

What is the function of the pancreas

Answer 54

The pancreas is a large gland situated below the stomach it produces pancreatic juice. The secretion contains proteases to hydrolyse proteins, lipase to hydrolyse lipids, and amylase to hydrolyse starch (pancreatic amylase)

Question 55

What is physical digestion

Answer 55

Physical digestion is where larger pieces of food is broken down into smaller pieces by the teeth, this makes it possible to ingest food but it also provides a large surface area for chemical digestion. And example of this is when food is churned by the stomach walls.

Question 56

what is chemical digestion

Answer 56

It is the hydrolysis of large insoluble molecules into smaller soluble ones. It is carried out by enzymes. All digestive enzymes function by hydrolysis what a water molecule is added. Enzymes are specific so more than one enzyme is needed to hydrolyse a large molecule

Question 57

Carbohydrate digestion

Answer 57

salivary Amylase is secreted into the mouth when saliva enters the mouth. This starts hydrolysing starch into maltose (disaccharide) it contains mineral salts that help to maintain pH around neutral this is the optimum pH for salivary amylase. then the acid in the stomach denatures the amylase from the mouth and prevents further hydrolysis of the starch. Food enters the small intestine where it mixes with pancreatic juice which contains pancreatic amylase. This hydrolyses starch to maltose.

Question 58

Which enzyme hydrolyses sucrose

Answer 58

sucrase

Question 59

Which enzyme hydrolyses lactose

Answer 59

lactase

Question 60

Lipid digestion

Answer 60

Lipids are hydrolysed by enzymes called lipases. They are produced in the pancreas and hydrolyse ester bonds found in triglycerides to form fatty acids and monoglycerides. A monoglyceride is a glycerol molecule with a single fatty acid molecule attached. Lipids (fats and oils) or split up into droplets called micells by bile salts. Which are produced in the liver this is called emulsification and increases the surface area of the lipids so that the action of lipases is sped up. Bile salts bind to fat droplets and break them down.

Question 61

Protein digestion

Answer 61

Proteins are hydrolysed by peptidases (proteases) there are a number of different proteases

ENDOPEPTIDASES-Hydrolyse peptide bonds between amino acids in the central region of a protein molecule. forming peptides.
EXOPEPTIDASES-Hydrolyse peptide bonds on the terminal amino acids of the peptide molecules formed by endopeptidases in this way they progressively release dipeptides and single amino acids.
DIPEPTIDASES-hydrolyse the bond between two amino acids of a dipeptide. Dipeptidases are membrane-bound and are a part of the cell surface membrane of epithelial cells in the ileum.

Question 62

structure of the ileum/small intestine

Answer 62

villi and microvilli- increase SA increasing rate of absorbsion
epithelial cell-network if capillaries for absorption
contain muscle- able to move, mentains diffusion gradients as their movement mixes the contents of the ileum. ensures products of digestion are absorbed
well supplied with blood vessels-carry away absorbed molecules and hence mentaining a diffusion gradient

Question 63

absorption of glucose

Answer 63

Sodium ions and glucose ions are co transported into the epithelial cell at the same time by facilitated diffusion and the use of a protein. That is now a high concentration glucose in the epithelial cell and that is a low concentration of glucose in the blood the blood is constantly moving in the capillaries. That is a low concentration of sodium ions in the epithelial cell as they are actively transported by a carrier proteins out of the cell and into the capillary [sodium potassium pump] this process requires energy in the form of ATP for active transport.

Question 64

Absorption of triglycerides

Answer 64

Larger lipid droplets are broken into smaller droplets when they fused with bile salts this process is called emulsification. This increases the surface area of the lipid droplets So lipase can digest the lipids. Bile is produced in the liver and it’s stored in the gallbladder and it is released into the small intestine.lipids are insoluble, and so they diffuse through the phospholipid bilayer of epithelial cells as they are hydrophobic and non polar. lipid droplets are transported to the smooth ER and golgi apparatus, where they are recombined to triglycerides. triglycerides associate with cholesterol and lipoproteins to form CHILOMICRONS. chilomicrons move out the cell by exocytosis and enter the lacteal, then into a blood vessel.

Question 65

Describe asthma lung disease

Answer 65

Triggered by smoke, pollen, allergens, Anxiety, exercise and even cold air

The muscles in the bronchi and bronchioles walls contract the diameter of the airway is reduced more mucus is secreted oh and the diameter of the airways is reduced even further. Cells can release a chemical called histamine and histamine causes the lining to become swollen.

Breathing becomes very difficult as they airways have narrowed, produces a wheezing sound as it is forced through a narrow airway less oxygen will diffuse into the blood through the Alveoli.

inhaler-contains drugs to relax muscles. and avoid allergens.

Question 66

Fibrosis lung disease [pulmonary fibrosis]

Answer 66

Permanent thickening of the lining of the lungs causes hard fibrous lumps [nodules] they form in the middle of the connective tissue that surrounds the alveoli. This makes the lungs very stiff and they lose their elasticity they are no longer able to expand normally during inhalation and do not collapse fully during exhaling. breathing becomes shallow.

shortness of breath, less oxygen taken in, chronic dry coughs, pain and discomfort in the chest, fatigue due to less O2 and less energy.

mining, quarrying industry, dust mites,

Question 67

emphysema lung disease

Answer 67

The lungs contain elastic tissue made of elastin. in emphysema the elastin is permanently stretched. lungs can’t force air out the alveoli and sometimes alveoli burst. reducing exchange of O2.

tobacco causes WBC to release protein digesting enzymes that break down alveolar walls. elastase enzyme breaks down elastin and elasticity is reduced.

Consequences-hard to move out of the lungs reduced surface area for gas exchange therefore blood is not oxygenated very well, causes shallow breathing and wheezing

no direct treatment, stop smoking to worsen

Question 68

Pulmonary tuberculosis lung disease

Answer 68

Pulmonary TB It’s caused by a disease called myobacterium tuberculosis. This bacteria is an aerobe and it needs oxygen and therefore the bacteria grows best and tissues with high oxygen concentration such as the lungs.

Symptoms-Persistent cough, tiredness, loss of appetite, Coughing up blood, chest pain, fever

Transmission-When people with TB cough, sneeze, laugh or talk they release tiny droplets of mucus and saliva containing the bacteria into the air transmission occurs when bacteria is inhaled.

Treatment-Involves a combination of 3 to 4 antibiotics. These are given over a 6 to 9 month period,To make sure the whole course of the treatment is completed so the bacteria is killed. However TB strains are very resistant to antibiotics and vaccination is only 70 to 80% effective.

Question 69

Give examples of antagonistic muscles

Answer 69

The external intercoastal muscles and the internal intercostal muscles

Question 70

What does antagonistic mean

Answer 70

when two pairs of something work together but in opposite directions. For example when the internal intercostal muscles contract the external intercostal muscles relax

Question 71

How do you know whether the diaphragm contracts or relaxes during inspiration or expiration

Answer 71

The diaphragm does whatever the external intercoastal muscles do. For example during inspiration the external intercoastal muscles contract therefore the diaphragm also contracts and moves upwards and outwards

Question 72

how do you know whether the volume of the throax/ throatic cavity increases Or decreases during inspiration

Answer 72

During inspiration pulmonary pressure is lower than atmospheric pressure. Therefore air forced into the lungs. Four pulmonary pressure to be low the volume of the thoracic cavity must increase.

Question 73

Define pulmonary ventilation

Answer 73

The total volume of air that has moved into the lungs during one minute