B4 - Organising animals/plants

Question 1

What is the blood?

Answer 1

a liquid tissue consisting of mainly plasma (a transportation medium) in which red + white blood cells and platelets are suspended

Question 2

What does the plasma carry?

Answer 2

-CO2 to lungs
-urea (from liver) to kidneys
-water
-small soluble products of digestion (glucose/amino acids) to individual cells

Always specify the products of digestion

It does not carry oxygen to cells

Question 3

What are 4 functions of the blood?

Answer 3

-transporting O2 + nutrients to individual cells
-carrying away waste products to excretory organs
-carrying WBC + antitoxins/antibodies to destroy pathogens
-forming blood clots at wounds to prevent excess blood loss + prevent infections

Question 4

Give 3 adaptations of the red blood cell:

Answer 4

-haemoglobin for oxygen to bind to, to be transported to cells for resp.
-biconcave disk (high SA:V)
-no nucleus to carry more oxygen

Question 5

Explain why having more red blood cells per unit volume is an advantage to athletes:

Answer 5

-more haemoglobin
-more oxygen can be transported to muscle cells
-increases rate of respiration in muscle cells
-more energy released for muscular contraction to bring about movement

Question 6

What is cardiac output and its formula?

Answer 6

-volume of blood pumped out of left ventricle per minute
-HRxSV

Question 7

What is the heart?

Answer 7

an organ that pumps blood around the body in a double circulatory system

Question 8

Name the parts of the heart in the order that the blood flows:

Answer 8

-vena cava
-right atrium
-right ventricle
-pulmonary artery (>lungs)

-pulmonary vein
-left atrium
-left ventricle
-aorta

Question 9

Why might having only one ventricle make the circulatory system less efficient?

Answer 9

-oxygenated blood would mix with the deoxy. blood
-so less oxygen reaches body cells

Question 10

What controls heart rate?

Answer 10

group of cells called the pacemaker in the wall of the right atrium

Question 11

Describe the features of an artery and what it does:

Answer 11

-carries blood away from heart and usually oxygenated (apart from pulmonary)

-thick elastic walls to withstand high blood pressures
-strong muscular tissues to pump the blood

ARTERIES DONT HAVE VALVES

Question 12

Describe the features of a vein and what it does:

Answer 12

-carries blood towards heart and usually deoxygenated (apart from pulmonary)

-thinner walls as it is lower pressure but has largest lumen
-valves that prevent backflow (blood squeezed back by skeletal muscles)

AND ARTERIES DONT HAVE VALVES

Question 13

What is the purpose of the capillaries?

Answer 13

exchanges substances with cells (gives nutrients/oxygen for resp. and takes away waste products)

Question 14

How are the capillaries adapted to their function?

Answer 14

-very small lumen but lots of them to increase SA
-always close to cells with one cell thick PPM for shortest diffusion distance

Question 15

What is meant by a double circulatory system?

Answer 15

-goes through heart twice with 2 systems for every 1 circuit around the body

-one system takes blood from heart to lungs and back to be oxygenated and allowing CO2 to be excreted
-other system pumps fully oxygenated blood from heart to the rest of the body

Question 16

Why is a double circulation system an advantageous feature?

Answer 16

-fully oxygenated blood and glucose can be pumped to the body very quickly (by the LV) to supply aero. resp.
-waste products are removed faster

-good for active animals

Question 17

Describe coronary heart disease:

Answer 17

-fatty deposits build up in the vessel walls of the coronary arteries, making their lumens thinner

-this reduces blood flow to the heart muscle tissue
-less O2 and glucose are transported to the heart muscle cells so they perform less aero. resp. and more anaerobically

-produces lactic acid, which poisons the heart muscle cells resulting in a heart attack

Question 18

Name 5 heart treatments:

Answer 18

-artificial pacemaker
-stents
-statins
-heart transplant
-heart valve transplant
(ASSHH)

Question 19

Describe stents and their pros/cons:

Answer 19

-wire cage mesh that holds arteries open

-effective quickly and can be used anywhere, long-lasting

-risk of blood clots/infection

Inserted with a method called balloon angioplasty, where a catheter with a balloon on it holds the cage, inflating it so it holds the artery open

Question 20

Describe what statins do and their pros/cons:

Answer 20

reduces production of “bad” cholesterol in liver (LDL)

-lowers risk of a fatty deposit build-up

-side effects + must be taken regularly

Question 21

How does an artificial pacemaker help? Describe its pros/cons:

Answer 21

electrical device used to correct irregularities when natural pacemaker has irregular rhythm

-stabilises HR and is long lasting

-batteries need replacing sometimes

Question 22

Describe what a heart transplant is and its pros/cons:

Answer 22

taking a donor heart and putting it into patient, can use artificial heart whilst waiting

-improved QoL + lifespan

-complex/expensive operation, immunosuppressants needed

Question 23

What is a heart valve transplant?

Answer 23

replacing a faulty valve with a porcine/mechanical valve

Faulty can mean it doesn’t open/close properly

Question 24

What are the features and consequences of a faulty valve?

Answer 24

-might not open/close fully (stiff/leaky)

-heart has to pump harder to deliver same amount of blood to body for respiration, causes shortness of breath and may result in heart failure

Question 25

What is breathing? Explain what happens physically when you in/exhale:

Answer 25

-ventilating the lungs with air -diaphragm contracts and flattens, intercostal muscles contract pushing ribcage up + out, chest volume increases, lower pressure draws air in -diaphragm relaxes and curves up, IC muscles relax and ribcage goes down, chest volume increases, higher pressure pushes air out

Question 26

Describe the process of gas exchange in the lungs:

Answer 26

-O2-rich air inhaled in alveoli, diffuses down steep CG across 1-cell thick PPM of the alveolus into the deoxygenated blood -at the same time, CO2-rich blood meets with the less concentrated air so it diffuses down the CG and into the exhaled air

Question 27

Name 3 adaptations of the alveoli:

Answer 27

-large net SA -rich blood supply (capillaries) to maintain steep CG -one cell thick PPM, shorter diff. path

Question 28

Describe the anatomical path taken by air inhaled into the body:

Answer 28

-nose/mouth -trachea -bronchi (>lungs) -bronchioles -alveoli

Question 29

Name and describe the 4 leaf tissue layers from top to bottom: ## Footnote Excluding the vascular bundle

Answer 29

-upper epidermis (includes WC, waterproof/transparent) -palisade mesophyll (lots of chloroplasts for PS) -spongey mesophyll (air spaces + large SA for gas exchange with stomata and palisade cells) -lower epidermis (stomata/GCs, control gas exchange/water loss)

Question 30

Describe the function of the xylem and the substances it carries:

Answer 30

transports water + mineral ions from roots to stem/leaves by the transpiration stream -water for PS and to hold itself upright -ions for **production of proteins/other molecules within cells**

Question 31

Describe the function of the phloem and the general function of substances it carries:

Answer 31

-transports dissolved sugars + cell sap made in leaves to the rest of the plant by **translocation** -used for respiration/growth/storage

Question 32

What is transpiration?

Answer 32

the loss of water vapour by evaporation from a leaf through the stomata

Question 33

How does water get from the soil to the stomata?

Answer 33

*transpiration stream* -osmosis into root hair cell then xylem -up through plant to leaf -spongey mesophyll, **osmosis out and evaporates in air space** -diffuses out of stomata ## Footnote In an exam, always say transpiration *stream*, rather than just transpiration

Question 34

Summarise how the volume of water lost from the leaves is controlled: ## Footnote Don't describe how it happens

Answer 34

opening and closing of the stomata

Question 35

Explain how the stomata and guard cells work together to regulate water loss:

Answer 35

more H2O - GC goes turgid and opens, to make an opening for water to be lost through less H2O - GC goes flaccid and closes hole, so water is conserved

Question 36

What *environmental* factors cause the stomata to open/close?

Answer 36

-open at day, closed at night (light in day, needs CO2 for PS) -if CO2 conc. inside drops, they open to allow more in for PS -wilting plants close stomata to lose less water

Question 37

What factors affect the rate of transpiration and why?

Answer 37

-temperature (higher temp., water vapour evaporates quicker from cells) -light intensity (more light, increases PS so stomata open more and let more water out whilst also letting CO2 in) -humidity (more humid, less transp.) -wind (more wind, CG more ventilated so water diffuses out quicker)

Question 38

How do you measure the rate of transpiration?

Answer 38

-mass of plant lost due to transpiration -volume of water absorbed by roots (using potometer, where bubble moves along scale)

Question 39

What do the root, stem, and leaves make up in a plant?

Answer 39

the transportation **organ system**

Question 40

How does oxygen get transported from the blood to the mitochondria?

Answer 40

diffusion down CG from blood across the cell membrane to mitochondria

Question 41

Why is it an advantage for a leaf to have less stomata on the top of the leaf?

Answer 41

-less water lost from direct sunlight -plant doesn't wilt

Question 42

What would happen if you left a plant with a potometer in a high temperature environment for a longer time?

Answer 42

-increased rate of transpiration -leaves lose too much water from stomata and wilt (cells are plasmolysed) -GCs also become plasmolysed, and so the stomata close to prevent excess water evaporation -potometer bubble stops moving ##Footnote It would stop moving if there was no more water to absorb