2.51 - 2.69 - Transport systems

Question 1

What is the role of the Phloem?

Answer 1

-Transports food materials manly sucrose and amino acids made from the plant from photosynthesising leaves to non-photosynthesising stems and roots
-Movement of sucrose can be transported in any direction in the plant
-The phloem structure is different from the xylem structure
-The cells are living cells and not hollow
-substances move cell to cell through pores in the ends wall of each cell
-The root, leaves and the stem form a plant organ system for the transportation of substances around the plant

Question 2

What is the structure and function of the xylem?

Answer 2

-Xylem vessels transport water and minerals from the from the roots to the stem and leaves
-Xylem is composed of dead cells which form hallow tubes
-Xylem are strengthened by lignin and so are adapted for the transportation of water in the transpiration stream

Question 3

What are root hair cells?

Answer 3

-Root hair cells are adapted for the efficent uptake of water(Osmosis) and mineral ions (Active transport)
-They grow between soil particles and absorb water and minerals from the soil
-Root hair cells increase the surface area to volume Ratio significantly by increasing the absorbtion of mineral ions by active transport
-The high proportion of dissolved minerals and sugars in the cytoplasm give it a low water potential

Question 4

What does the root hair cell look like?

Answer 4

Question 5

What is the route of water through the plant?

Answer 5

Question 6

What is Transpiration?

Answer 6

-Transpiration is the loss of water vapour from the parts of the plant that are above the ground
-loss of water occours through the evaporation of water at the surface of the spongy mesophyll cells followed by diffusion of water vapour through the stomata
-The many interconnecting spaces between the mesophyll cells and the stomata creates a large surface area
-this means evaporation can happen quickly when the stomata is open

Question 7

What is the effect of transpiration?

Answer 7

-water moves through the xylem vessels in a continuous transpiration stream from the roots to the leaves via the stem to replace the water that has been lost to transpiration
-The water in the xylem creates an unbroken column
-Transpiration produces tension ‘or pulls’ on the water in the xylem vessels
-If the rate of transpiration from the leaves increases, water molecules are pulled up the xylem vessel quicker

Question 8

What is the function of transpiration?

Answer 8

-Transporting mineral ions
-Providing water to keep the cells turgid in order to support the structure of the plant
-Providing water to the leaf for photosynthesis
-Keeping the leaves cool, the conversion of water into water vapour reduces heat energy and cools down the plant

Question 9

What are the factors effecting the rate of transpiration

Answer 9

-Air movement, more- good air flow removes water vapour from the air surronding the leaf which sets up a concentration gradient between the leaf and the air, increasing water loss

-Humidity, less- a high level of humidity, humidity is measure of moisture in the air and when the air is saturated with water vapour the concentration gradient is weaker so less water is lost

-Tempreture, more- at higher tempretures particles have more kinetic energy so transpiration occours faster rate as water molecules evaporate from the mesophyll and diffuses away faster than at lower tempretures

-Light intensity, more, guard cells are responsive to light intensity and when it is high they are turgid and the stomata open allowing water to be lost

Question 10

What are the components of blood?

Answer 10

Blood consists of red blood cells white blood cells, platelets and plasma
Over half the volume of the blood is made up of plasma
The majority of the other half is made up of red blood cells
The remaining fractions consist of white blood cells and platelets

Question 11

What are the blood components?

Answer 11

Red blood cells- Biconcave discs containing no nucleus but a lot of the protein Haemoglobin
White blood cells- Large cells containing a big nucleus, different types have slightly different structures and functions
Platelets- fragments of cells
Plasma-straw coloured liquid

Question 11

What are the adaptions of the plasma?

Answer 11

Plasma is a straw coloured liquid which other components of blood are suspended with

• carbon dioxide the waste product of respiration, dissolved in the plasma as hydrogen carbonate ions are transported from respiring cells to the lungs

-digested food and mineral ions- dissolved particles absorbed from the small intestine and delivered to requiring cells around the body

Urea- The waste substances produced in the breakdowns of proteins by the liver urea is dissolved in the plasma and transported to the kidneys

Question 12

What are the adaptions of the red blood cells?

Answer 12

Red blood cells are specialised cells which carry around oxygen to respiring cells they have three adapting functions
-They are full of haemoglobin a protein that binds to oxygen to form oxyhaemoglobin
-They have no nucleus which allows for more space for Haemoglobin to be packed in
-The shape of a red blood is described as being a ‘biconcave disc’ this shape gives them a large surface area to volume ratio to maximise diffusion of oxygen in and out

Question 13

What are the adaptions of white blood cells?

Answer 13

White blood cells are part of the body’s immune system
These specialised cells defend against pathogenic microorganisms
There two main types of white blood cells
Phagocytes- carry out phagocytosis by engulfing and digesting pathogens
-Phagocytes have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells
-once they encounter a pathogenic cell, they will engulf it and release a digestive enzyme to digest it
-there is a non specific immune response

Lymphocytes
-Lymphocytes produce anti bodies
-Anti bodies are Y shaped proteins with a shape that is specific to the antigens on the surface of the pathogens (bacteria)
-This is a specific type of immune response as the anti bodies produced will only fit one type of antigen on a pathogen

-Antibodies attach to the antigens and cause agglutination (clumping together0
-This means that the pathogenic cells cannot move very easily
-At the same time chemicals are released that signal to phagocytes that there are cells present that need to be destroyed
Lymphocytes also produce anti toxins to neutralise the toxins released by the pathogens

Question 13

What are the adaptions of Platelets?

Answer 13

-Platelets are involved in helping the blood clot
-Platelets are fragments of cells that are involved in blood clotting and forming scabs where the skin has been cut or punctured
-When skin is broken the platelets arrive to stop the bleeding
-A series of reactions take place within the blood plasma
-Platelets release chemicals that cause soluble fibrinogen proteins to convert into insoluble fibrin and form an insoluble mesh across the wound, trapping red blood cells there to form a clot
-the clot eventually dries and develops into a scab to protect the wound from bacteria entering

Scab formation forms a wound that prevents microorganisms that could infect, it remains there until new skin has grown underneath sealing the skin

Question 14

How does exercises effect the heart rate?

Answer 14

-The heart pumps blood around the body in order to supply glucose and oxygen to respiring cells
-The blood also removes waste products from respiring cells
-During excerise the cells of the muscles respire more rapidly in order to provide more energy for muscle contraction
-Respiration is aerobic if excerise is moderate but if it is intense it is anaerobic
-An increase in respiration means an increase in requirement for oxygen and glucose as well as an increase in production of waste products that need to be removed
The nervous system responds to this by stimulating changes
-Heart rate increases to deliver oxygen and glucose and remove waste more frequently
-The volume of blood pumped out of the heart also increases to deliver bigger quantities of oxygen and blood
-Production of the hormone adrenaline increases heart rate as part of a’ fight or flight’ movement
-At the end of the period of excerise the heart rate may remain high for a period of time as oxygen is required in the muscles to break down the lactic acid from anaerobic respiration
-the time taken for the heart to return to its resting rate is the recovery time

Question 15

What are the blood vessels in the human body?

Answer 15

-Arteries
-Veins
-capillaries

Question 16

What are the features of the arteries?

Answer 16

-Carry blood at high pressure away from the heart
-Carry oxygenated blood ( except the pulmonary artery)
-Have thick muscular walls containing elastic fibres
-Have narrow lumen
-Blood flows at fast speed
The structure of the arteries is adapted to its function thick muscular walls containing elastic fibres help to withstand the high blood pressure and maintains the blood pressure the narrow lumen also helps to maintain a high blood pressure

Question 17

What are the features of the veins?

Answer 17

-Carry blood at low pressure towards the heart
-Carry deoxygenated blood (other than the pulmonary vein
-Have thin walls
-Have large lumen
-Contain valves
-Blood flows through at low speed
The structure of the vein is adapted to its function like A large lumen reduces resistance to blood to flow under low pressure
Valves prevent backflow of blood as its under a low pressure

Question 18

What is the features of the capillaries?

Answer 18

-carry blood at low pressure within tissues
-Carry both oxygenated blood and deoxygenated blood
-Have walls that are one cell thick
-Have leaky walls
-Speed of blood flow is slow
The structure of a capillary is adapted to its function by having one cell thick walls so substances can easily diffuse in and out. The leaky walls allow blood plasma to leak out and form tissue fluid surrounding cells

Question 19

How is the circulatory system composed?

Answer 19

The circulatory system consists of a closed network of blood vessels connected to the heart
-Oxygenated blood is carried away from the heart and towards organ and arteries
-These narrow to arterioles and then capillaries as they pass through the organs
-In the organs, respiring cells use up the oxygen from the blood
-The capillaries widen the venules and finally veins as they move away from the organs
-Veins carry deoxygenated blood back towards the heart

Question 20

What is the structure and function of the heart?

Answer 20

-The heart organ is a double pump
-Oxygenated blood from the lungs enters the left side of the heart and is pumped to the rest of the body
-The left ventricle has a thicker muscle wall than the right ventricle as it pumps blood at a high pressure around the entire body
-Deoxygenated blood from the body enters the right side of the heart and is pumped to the lungs
-The right ventricle is pumping blood at a lower pressure to the lungs a muscle called the septum separates the 2 sides of the heart
-Blood is pumped to the heart in the vein and out of the heart in the arteries
-The coronary arteries supply the cardiac muscles tissue of the heart with oxygenated blood because the heart is a muscle that is coastally working it requires a lot of oxygen

Question 21

What is the structure of the heart?

Answer 21

Question 22

What are the responses to infection?

Answer 22

The pathogen enters the blood stream and multiplies
A release of toxins (in the case of bacteria) and infection of body cells causes symptoms in the patient
Phagocytes that encounter the pathogen recognise that it is an invading pathogen and engulf and digest (non-specific response)
Eventually, the pathogen encounters a lymphocyte which recognises its antigens
The lymphocyte starts to produce specific antibodies to combat that particular pathogen
The lymphocyte also clones itself to produce lots of lymphocytes (all producing the specific antibody required)
Antibodies cause agglutination of pathogens
Phagocytes engulf and digest the agglutinated pathogens
After the patient has recovered, they retain antibodies specific to the disease as well as memory cells (lymphocytes that recognise the pathogen)
If the patient encounters the same pathogen again, it will trigger a secondary immune response
Memory cells can produce much larger quantities of the required antibody in a much shorter time to fight off the pathogen before the patient suffers any symptoms

Question 23

What are Vacines?

Answer 23

Vaccines are used to induce immunity to infectious diseases
A vaccine contains harmless versions of a pathogen

Question 24

How do vaccines killing?

Answer 24

Killing the pathogen
Making the pathogen unable to grow or divide (attenuated vaccine)
Using fragments of pathogens, rather than whole cells

Question 25

How do Vaccines work?

Answer 25

Lymphocytes recognise the antigens in the bloodstream
The activated lymphocytes produce antibodies specific to the antigen encountered
Memory cells and antibodies subsequently remain circulating in the blood stream

Future infection by the same pathogen will trigger a response that is much faster and much larger compared to the initial response
Due to the rapid nature of the response, the pathogen is unable to cause disease and the individual is said to be immune

Question 26

What are the importance’s of Vaccination?

Answer 26

Vaccines not only protect the vaccinated individuals, they also reduce the likelihood that an infected individual will spread the pathogen to others
This can prevent the spread of the disease
Vaccines have reduced the cases of certain diseases drastically or even eradicated many diseases worldwide
This includes smallpox, measles, mumps and tetanus amongst many others

Question 27

What are the disadvantages of Vaccinations?

Answer 27

There are some disadvantages to vaccinations that reduce how effective vaccination programs can be
Mutations in the pathogen’s DNA/RNA can result in significant changes to the antigen of the pathogen meaning that lymphocytes no longer recognise the pathogen
Side-effects of vaccinations can reduce the uptake in the population

Question 28

How does Coronary heart diseases happen?

Answer 28

Like all cells in the body, cardiac muscle cells need a supply of blood to deliver oxygen and glucose and to remove waste products such as carbon dioxide
The blood is supplied to the heart by the coronary arteries which branch off directly from the aorta
The heart needs to constantly respire, so it is vital that it receives oxygen

In coronary heart disease (CHD), layers of fatty material (plaque) build up inside the coronary arteries
These fatty deposits are mainly formed from cholesterol
There are two sources of cholesterol in the body:
Dietary cholesterol (from animal products eaten)
Cholesterol synthesised by the liver

Question 29

How can the Coronary artery become blocked

Answer 29

The flow of blood through the arteries is reduced, resulting in a lack of oxygen for the heart muscle
Partial blockage of the coronary arteries creates a restricted blood flow to the cardiac muscle cells and results in severe chest pains called angina
Complete blockage means cells in that area of the heart will not be able to respire aerobically, leading to a heart attack
Treatment of CHD involves either increasing the width of the lumen of the coronary arteries using a stent, or prescribing statins to lower blood cholesterol

Question 30

What are the risk factors of Coronary heart diseases?

Answer 30

Obesity
Carrying extra weight puts a strain on the heart
Increased weight can lead to Type 2 diabetes which further damages your blood vessels
High blood pressure
This increases the force of the blood against the artery walls and consequently leads to damage of the vessels
High cholesterol
Speeds up the build up of fatty plaques in the arteries leading to blockages
Smoking
Chemicals in smoke cause an increase in plaque build up and an increase in blood pressure
Carbon monoxide also reduces the oxygen carrying capacity of the red blood cells

Question 31

What are the main blood vessel of the circulatory system?

Answer 31