P1: Module 3: Exchange and Transport Flashcards
Suggest why the Titicaca water frog has evolved to have large skin folds
Increases Sa:Vol which Increases the rate of O2 absorption as O2 levels in lake are low
When out of water the Titicaca frog is able to use its lungs to absorb O2. Their lungs contain gaseous exchange surfaces. Describe and explain 3 features of the lungs provides an efficient gas exchange surface
-Large SA; for maximum diffusion
-Aveolar wall is only 1 cell thick; provides a short diffusion distance
-Good blood supply; maintains a conc gradient
What muscle in mammalian ventilation system contract to force air out of the lungs?
Internal intercoastal muscles
Describe exhalation in a mammal
-Ribcage moves downwards and inwards
-External intercoastal muscles relax
-Diaphragm relaxes
Sjogren’s syndrome is a rare condition that can reduce the production of mucus. Suggest how the upper respiratory tract of a person with Sjogren’s syndrome might be affected
More infections and coughing
Why can expiration be a passive process?
It doesn’t use muscle contraction
Some chemicals can act as allergens. If these allergens are inhaled they can cause breathing problems. Allergens cause the smooth muscle in the walls of the airways to contract.
Suggest the effects that this muscle contraction has on ventilation (2)
-As lumen diameter reduces; its harder to exhale and inhale
Closed circulatory system
Blood stays in blood vessels
Suggest two differences between closed circulatory system of sea bass and of a mammal
-Sea bass= single whilst mammal= double
-Sea bass goes through heart once whilst mammal goes through heart twice
Outline why insects and other animals need well developed transport systems
Have high metabolic rate; so need large O2 supply; Has low SA:Vol; so diffusion would be too slow as distance is too far
Explain why SA:Vol determines whether an organism needs a circ. system
Larger organisms have small SA:Vol; so rate of diffusion would be too slow as distance is too far; for sufficient uptake of O2
Compare circ. systems of mammals and fish (6)
BOTH: -Closed systems (blood stays in blood vessels)
-Both have a heart
-Both carry O2 using hB
DIFF: -Fish= single circ (blood in heart once) whilst mammals=
double circ.
-Fish= one atrium and one ventricle so no septum whilst
mammals= have two atrias and two ventricles w/ a
septum
-Fish= blood pressure is lower to organs whilst
mammals= blood pressure is maintained at higher
pressures
Describe how the structure of each blood vessel is adapted to its function
Artery:
-FUNC= carry blood away from heart under high
pressure
-STRUC= has thicker elastic layer enables them to
stretch and recoil and helps withstand the high
pressure; has collagen which provides support, maintains shape by limiting stretch.
Veins:
-FUNC= carry blood back to heart, under less pressure than arteries
-STRUC= thinner elastic layer and has valves to prevent backflow. Has more collagen than arteries to give structural support as they carry large volumes of blood
Capillaries:
-FUNC= allow substances to exchange between blood and surrounding cells
-STRUC= walls are one cell thick which allows a short diffusion distance, its only large enough to allow RBCs to travel through in single file this increases the contact of RBC to capillary wall
Explain why oncotic pressure of blood depends only on conc of large plasma proteins (2)
Large plasma proteins cant pass through capillary wall but other solutes can; imbalance of large plasma proteins between blood and tissue fluid results in oncotic pressure
VSD is a hole in the septum of the heart. Why would people w/ VSD get easily tired
Blood leaks from the left to right ventricle’s during ventricular systole; more oxygenated blood delivered to lungs ; deoxygenated blood passes into left ventricle during atrial systole; less oxygenated blood pumped around body so less O2 available for aerobic respiration
Why does diastole follow systole in mammalian heart?
Cardiac muscle takes a short time to repolarise after being stimulated
Outline why its important that fetal hB has a higher oxygen affinity than adult hB
Fetal recieves sufficient oxygen for respiration; maintains O2 conc gradient
Suggest why reduced heart rate is sometimes seen in people who are very aerobically fit
Increased volume of ventricle
-Increased strength of muscle heart
RBCs contain very high conc of enzyme carbonic anhydrase, a scientist planned to investigate the effect of pH on the activity of carbonic anhydrase.
State 2 factors that the scientist would need to control during this investigation (2)
-Temperature
-Enzyme conc
Human blood is maintained at pH 7.4 by reactions that occur in RBs. Use your knowledge of these reactions to explain how a pH of 7.4 is maintained (3)
H+ reacts w/ hB to form haemoglobinic acid which lowers pH back to 7.4; H+ reacts w/ HCO3- to form H2CO3 which lowers pH back to 7.4; H2CO3 dissociates to form H+ and HCO3- which raises pH back to 7.4
Explain why large multicellular plants need a transport system (3)
Small SA:Vol so diffusion would not fast enough as there’s long distance from external surface to cells
Multicellular organisms eg plants have evolved internal transport systems. Explain the benefit of plants having internal transport systems
SA:Vol small; transport system ensures nutrents/ water reaches all tissues
NaCl dissociates into Na+ and Cl-. Explain how casparian strip prevents these ions from reaching the xylem of the plant by apoplast pathway
Phospholipid bilayer repels charged particles; forces water to pass through plasma membrane
Soluble mineral ions are present in soil. Explain why water molecules can form H bonds with the nitrate (NO3-) ions
Water is a polar molecule; NO3- is negative; H bonds between H on water and O on nitrate formed
State one similarity and two diff between structure of xylem and phloem
-SIMI: both made up of cells joined end to end
-DIFF: -x= lignified p= not lignified only contains cellulose
-x= no companion cells p= companion cells
Mosses are small plants. Suggest why they don’t need roots or xylem to survive
Large SA:Vol; distance water/ ions need to travel is short so they dont need roots or xylem
State the function of pits in xylem tissue
Lateral movement of water
Explain one practical precaution that should be taken when using a potometer
Dont allow air to enter cut shoot underwater at an angle to prevent airlock/ ensures a continuous column of water
A student selected diff tomato plant leaves and sealed a plastic bag over each w/ a paper clip, he did the same for watermelon leaves. The plastic bags were left for 6 hours then they used a syringe to collect any water inside, identify 2 problems and solutions
-Water accumulating in bag which decreases transpiration; solution; record for shorter time eg less than 6 hours
-Ppaer clip seal isnt completely airtight so water vapour may escape; soltion= use sticky tape or elastic band
Describe how a potometer can be used to calculate more accurate value of transpiration
Ensure the leaves are dry, making it airtight, cutting shoot underwater at an angle; measure distance of air bubble travels per interval calculate vol of water uptake maintain constant conditions
Name and describe 2 pathways water takes to reach xylem at base of stem
-Symplast= plasmodesmata
-Apoplast= cell wall
Adhesion
Attraction of water molecules to impermeable walls of xylem tissue
Theres 2 Q:
Sucrose is carried in phloem sap from source to sink
1) Explain why starch isn’t transported in the sap
2) Suggest why sucrose is more suitable transport than glucose
1)Starch isnt soluble in water
2)Sucrose is less likely to be used in respiration
Explain how mass flow of phloem sap occurs in plants with a vascular system
Assimilates enter sieve tube in phloem at sources which lowers water pot. of sieve tube; water enters sieve tube by osmosis and increases hydrostatic pressure; assimilates leave sieve tube at sink and increases water pot inside sieve tube; water leaves which lowers hydro pressure; assimilates move from high to low hydrostatic pressure
Explain with an example how some parts of plant can act as both a source and sink
Certain parts can store and release carbohydrates when needed; eg root which can act as sink or source at diff times of year
Explain the process of loading sucrose into phloem and its movement in the phloem
Sucrose pumped into companion cell; by active transport; H+ is a co transport of sucrose; Sucrose diffuses into phloem sieve tube; water enters sieve tube element from companion cell; water enters sieve tube element from xylem; increased pressure forces flow of sap down phloem; through pores in sieve plates
Define the term magnification.
How many times bigger a microscope image is compared to the original specimen.
Define the term resolution
The shortest distance between two objects that are still seen as separate objects.
Describe how to prepare slide to be used with a light microscope
Cut the specimen very thinly
Use forceps to put it in the middle of the glass slide.
Pipette two drops of water onto the specimen.
Add a stain, if necessary.
Place a cover slip on top
Being careful not to create any air bubbles
Function of Nucleus, Nucleolus, Nuclear envelope
Nucleus Controls the cell’s activities Contains the DNA / chromosomes
Nucleolus Produces ribosomes
Nuclear envelope Double membrane around the nucleus Has pores that allow mRNA to leave the nucleus
Function of Rough ER, Smooth ER, Golgi apparatus
Rough ER Processes and folds proteins
Smooth ER Synthesises and processes lipids
Golgi apparatus Processes and packages proteins into vesicles
Function of Plasma membrane, Centrioles, Cell Wall, Flagella, Cilia, Vesicle
Plasma membrane Controls the movement of substances into and out of the cell Has receptor molecules used in cell signalling
Centrioles Pull the chromosomes / chromatids to opposite poles during cell division
Cell Wall Supports the plant cell
Flagella Allow movement of the cell
Cilia Cilia move to move substances along the cell surface
Vesicle Transports substances in and out of the cell
Explain why some organisms need specialised exchange surfaces. (3)
They have a small surface area to volume ratio
High metabolic rate
Some cells are too deep in the body for rate of diffusion alone to supply the cells
It is more difficult for moths and bumblebees to maintain their body temperature than for
mammals and birds to maintain their body temperature.
Explain why.
(insects are smaller and) have a , large(r) / AW , surface
area to volume ratio
(insects have) greater rate of heat loss
mammals and birds have , more effective / thicker ,
insulation
