Biology Component 3 - 3.1 Adaptations for Gas Exchange - Flashcards in A Level and IB Biology

In Insects, Mammals, and Fish, what is the benefit of a large surface area?

Insect - large number of tracheoles linking directly to the tissues; Mammal - large number of alveoli provides a large SA for gas exchange/folded wall of alveoli; Fish - Large number of gill filaments with a large number of gill plates

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In Insects, Mammals, and Fish, what is the benefit of a thin/one cell thick membrane?

Insect - shorter diffusion pathway between tubes and cells; Mammals - layer of squarmous epithelial cells/1 cell thick for a short diffusion pathway; Fish - One cell thick gill plates for a short diffusion pathway

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In Insects, Mammals, and Fish, what is the benefit of maintaining a concentration gradient?

Insect - ventilation to ensure movement of gases; Mammals - Large networks of capillaries/Ventilation of the lungs; Fish - Counter-current flow is setup between the blood in the capillaries and the water/blood flows opposite direction to water

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In Insects and Mammals, what is the benefit of the gas exchange surface being moist?

Insect - fluid filled tracheoles (O2 and CO2 can dissolve/diffuse quickly); Mammals - Dissolve and diffuse O2 and CO2 in the alveoli

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In Insects, Mammals, and Fish, what is the benefit of a permeable gas membrane?

Insect - O2 and CO2 can diffuse through cell membrane; Mammals - Alveoli are permeable to O2 and CO2; Fish - Gill plates are permeable to O2 and CO2

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Describe Bony Fish

Skeleton made of bones; live in sea & fresh water; covered in scales (no gas exchange through surface); contain gills in the opercular cavity; gas exchange involves a counter-current system

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Describe Cartilaginous Fish

Skeleton made of cartilage; mostly live in sea; covered in scales (no gas exchange through surface); contain gill clefts; gas exchange involves a parallel system (water and blood in same direction)

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Are external or internal gills exchange systems better?

External gills are better than internal - internal requires a ventilation system

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What is the Scientific Term for a mouth?

Buccal Cavity

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Describe the Fish Gas Exchange System

It is a gill plate - one gill contains a gill arch and filament(s); fish and insects have a one-way flow system of ventilation

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Describe the thoracic pressure control in humans

Internal pressure lower than air pressure (negative pressure) = breath in | Internal pressure higher than air pressure (positive pressure) = breath out

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What muscles does breathing require?

External Intercostal Muscle

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What happens when you breath in?

Rib Cage goes up/out; Outer Pleural Membrane goes up/out; Inner Pleural Membrane goes up/out; Lung expands, alveoli pressure decreases, air rushes in

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What surrounds the lung?

Two membranes (Pleural); Fluid Filled Space between them (Pleural Cavity) to lubricate movement and act as a shock absorber; Pleural Membranes ensure thorax is air tight, changes in volume of thorax must be converted to pressure changes in the lung

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Describe the adaptations to increase SA:Volume ratio, method of delivery of oxygen to cell, and the habitat of an Amoeba

Single cells have large SA:Volume ratio/very thin cell membrane to allow rapid diffusion; Diffusion through a thin cell membrane; Ensures rapid oxygen into the cell, removes CO2 rapidly to prevent build up; Protoctista Kingdom

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Describe the adaptations to increase SA:Volume ratio, method of delivery of oxygen to cell, and the habitat of a Flatworm

Dorso (ventrally flattened), short diffusion pathway; diffusion across the cell membrane to provide O2 required; low O2 requirement; all cells are close to respirator surface, Animalia Kingdom

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Describe the adaptations to increase SA:Volume ratio, method of delivery of oxygen to cell, and the habitat of an Earthworm

Elongated and thin. thin outer cell membrane to diffuse gas quickly; diffusion across cell membrane and O2 transport by haemoglobin; haemoglobin present in blood to transport oxygenated blood, low O2 requirement; low metabolic rate, Animalia Kingdom

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List the structure of the ventilation system (starting with tongue, ending with bronchioles)

Tongue, Epiglottis, Oesophagus, Trachea (Cartilage Rings with Intercostal Muscles in the Ribs), Bronchi, Bronchioles (Diaphragm at the bottom of the lungs)

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What is the function of the ciliated epithelial layer?

To waft mucus up the throat into the mouth to be swallowed or destroyed; removal of harmful particles from the air by trapping in the mucus

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What is the function of the layer of cartilage in the Trachea?

Supports the trachea and bronchi; prevents collapse during inhilation when there are pressure changes sucking the air in

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Suggest why the cartilage is not in the form of a complete ring

To allow the oesophagus to expand into the trachea

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What is the function and the position of the goblet cells?

Secrete sticky mucus to trap tiny particles; in the trachea, near the ciliated epithelial cells (bronchi, larger bronchioles)

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What is the function and the position of the ciliated epithelial cells?

Wafts mucus up the trachea using cilia; trachea, bronchi, larger bronchioles

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What is the function and the position of the cartilage?

Supports the opening of the trachea and holds them open during inspiration; surrounding the trachea and bronchi and large bronchioles

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What is the function and the position of the elastic fires?

Prevents the alveoli from bursting by stretching and recoiling; found all over the inspiration system

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What is the function and the position of the smooth muscle?

Adjusts the size of the airway to restrict airway if lumen is too small; trachea, bronchi and larger bronchioles

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Describe the inspirational system in ventilation

External intercostal muscle contract, pulling the ribcage up and out; diaphragm contracts pulling it from a domed to a flattened shape; combined effect is: volume of the thorax and lung increases; pressure decreases; air enters

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Describe the expiration system in ventilation

External intercostal muscle relax, ribcage falls down and in; diaphragm relaxes pushing it into a flattened shape; elastic recoil of lung tissue; combined effect is: volume of the thorax and lung decreases; pressure increases; air leaves

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What happens to amphibians as they grow older?

When they are young and aquatic, they have gills; when they are adult and terrestrial, they have lungs

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What is the gas exchange organ in a plant?

Leaf (gas exchange system is the spongy mesophyll layer); CO2 required for photosynthesis, O2 required for AEROBIC respiration

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Describe the structure of the leaf from top to bottom

Cuticle, Upper Epidermis, Pallisade Mesophyll Layer, Spongy Mesophyll Layer, Stoma (Stomata = 2+), Guard Cells on the Lower Epidermis

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Multicellular animals have a small SA:Volume Ratio and generally a high metabolic rate. What effect will this have on their oxygen requirement?

Increases their O2 requirement.

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Describe whether amphibians are terrestrial/aquatic, what their gas exchange surface is, and features of the surface

Aquatic (young) and Terrestrial (adult); moist skin as a respiratory surface and uses lungs when active; undergo metamorphosis, larvae have gills, adults use their skin for gas exchange at rest

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Describe whether reptiles are terrestrial/aquatic, what their gas exchange surface is, and features of the surface

Terrestrial; lungs (more complex than amphibians, increasing SA for gas exchange) and no diaphragm; movement of the ribs aid in the ventilation of the lungs and in-growth of tissue increases SA

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Describe whether birds are terrestrial/aquatic, what their gas exchange surface is, and features of the surface

Terrestrial; lungs (two sets of air sacs to aid in efficient breathing), no diaphragm present, and flight muscles assist with ventilation; attached to lungs are air sacs which act as bellows, lungs always filled with fresh air

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What is the Gas Exchange System in Insects?

Tracheal System - Spiracles located on the body surface (guarded by fine hairs to keep foreign particles out by valves that function to open/close spiracles

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What do spiracles open to?

They open into long tubes called the lateral tracheal truck that link to air sacs and tracheae; the tracheae are fine tubes that have a wall of single layered epithelial cells.

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What does the single layer of epithelial cells secrete?

Cuticular thickening around the tubes to support the tubes

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What does the tracheal tubes branch into?

Tracheoles - they enter all the tissue and sometimes, even the cells of the insect; ends of the tracheoles that are in the tissue are filled with fluid and lack cuticular thickenings.

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What happens to the muscles during flight in insects?

The fluid at the end of the tracheoles is drawn into the tissue to supply oxygen; creates larger SA for gas exchange and a shorter diffusion distance; fluid released back into the tracheole so CO2 can be removed

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Explain how the structure of the gas exchange system of an insect ensures that there is a large surface area for gas exchange

Large number of tracheoles

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Where are the gills located in a fish?

Opercular Cavity (Buccal Cavity) and a chamber at the sides of their mouth called the operculum

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What happens when fish inhale?

Buccal Cavity opens, operculum (gill cover/valve) closes, floor of the Buccal Cavity is lowered, volume of the Buccal Cavity increases and the pressure falls; water is pulled in

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What happens when fish exhale?

Buccal Cavity closes, floor of the Buccal Cavity raises, volume of the Buccal Cavity decreases and the pressure increases, water flows across the fills, Operculum is forced open

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What is each gill composed of?

2 rows of filaments increasing the Surface Area; each filament has lamellae, each covered in many tissue flaps called gill plates; increases SA; small diffusion pathway; gill plates contain capillaries - counter-current flow

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Describe counter-current flow

Blood flow across gill plates; blood flows in opposite direction (maximum exchange of oxygen); more efficient than parallel system; in parallel system, diffusion occurs until blood and water have equal percentage saturation of oxygen (equilibrium)

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What is the palisade mesophyll?

Main photosynthetic tissue - deep and packed full of chloroplasts which are able to move and so arrange themselves in a position that gives maximum light absorption.

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What is the upper epidermis?

Single layer of cells that is transparent since no chloroplasts are present, meaning that light can pass straight through; not many stomata in the upper epidermis since the heat from direct sunlight would cause excessive evaporation

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What is the cuticle?

Upper surface of leaf is covered by a waxy cuticle to significantly reduce water loss

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What is the spongy mesophyll?

Fewer chloroplasts so it is less important for photosynthesis; loosely packed and have a large number of air spaces; moist surfaces for gas exchange; CO2 diffuses out in the opposite direction; larger SA for gas exchange

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What is the lower epidermis?

No waxy cuticle but has a large number of stomata; open to allow diffusion of gas into/out of the leaf; water evaporates from the surfaces of spongy mesophyll cells into the air spaces and diffuses out through stomata as water vapour

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What is the scientific name for the upper epidermis?

Adaxial Surface

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What is the scientific name for the lower epidermis?

Abaxial Surface

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How do Guard Cells open?

K+ ions are actively transported into guard cells; starch is converted into malate to balance the charge; water potential in the guard cells lowers; water enters the guard cells by osmosis; guard cells swell and become turgid and the cells curve

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How do Guard Cells close?

K+ ions are diffused out of the cell; water potential in the guard cells increase; water exits the guard cells by osmosis; pressure inside the cell decreases and the cells return to its original shape - plasmolysed

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Give two explanations as to why the rate of water loss during gas exchange is very low in most insects

Open/close sphericals to reduce unwanted gas exchange to limit water loss; tracheal system means gas exchange through the exoskeleton does not occur

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Describe and explain how the counter-current system leads to efficient gas exchange across the gills of a fish

Blood and water flow in opposite direction; maintains concentration along the whole plate; blood always meets water with a higher O2 saturation

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Biology Component 3 - 3.1 Adaptations for Gas Exchange

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