OCR A Biology Module 3: Exchange Surfaces, Transport in Animals & Plants

What is the effect of a good blood supply on gas exchange?

It helps maintain concentration gradients by quickly transporting gases away from exchange surfaces.

What adaptations do insects have for gas exchange?

They use a tracheal system that delivers oxygen directly to tissues.

What is the role of external intercostal muscles during inhalation?

They contract to pull the ribcage up and out, increasing thoracic volume.

What occurs during relaxed expiration?

The diaphragm and external intercostal muscles relax, allowing the thorax to decrease in volume.

What does vital capacity measure?

The maximum volume of air an individual can inhale and exhale during a deep breath.

What is the significance of gill lamellae in gas exchange?

They provide a large surface area and short diffusion distance for gas exchange.

What is the role of spiracles in insects?

They are valve-like structures that open and close to allow gas exchange and prevent water loss.

How do insects maintain a concentration gradient for gas exchange?

By contracting and relaxing abdominal muscles to pump air in and out.

What provides a large surface area for gas exchange in insects?

The many branching tracheoles.

What is the importance of short diffusion distances in gas exchange?

It allows for efficient gas exchange due to thin walls of tracheoles.

What is the primary challenge fish face regarding oxygen in water?

Water has a lower dissolved oxygen concentration compared to the atmosphere.

Why is maintaining a steep concentration gradient essential for gas exchange?

It maximizes diffusion efficiency across the respiratory surfaces.

What maintains the concentration gradient in cells?

Cells respiring, using oxygen and producing carbon dioxide.

What happens to insects' respiration during flight?

Muscles contract rapidly, leading to anaerobic respiration and lactate production.

What is the function of the tracheal fluid in insects?

It facilitates gas exchange and helps maintain pressure in the tracheoles.

What is an open circulatory system?

A system where the transport medium (haemolymph) is pumped directly into the body cavity (haemocoel).

What is the systemic circuit?

The circuit that carries blood from the heart to the rest of the body.

What is the importance of surface area to volume ratio in organisms?

It affects the efficiency of substance exchange, with larger ratios facilitating easier transport.

How do smaller organisms like amoeba exchange substances?

They rely on simple diffusion due to their large surface area compared to volume.

Why do larger organisms require special adaptations for gas exchange?

They have a smaller surface area to volume ratio and higher metabolic rates, necessitating efficient transport systems.

What structures are involved in the mammalian gas exchange system?

The trachea, bronchi, bronchioles, and alveoli.

What is the function of the trachea?

It supports air flow to the lungs and is lined with ciliated epithelial cells and goblet cells.

What role do goblet cells play in the trachea?

They produce mucus that traps pathogens and dust particles.

How do ciliated cells in the trachea contribute to respiratory health?

They sweep mucus upwards to prevent pathogens from reaching the lungs.

What happens to the smooth muscle in the trachea when harmful substances are present?

It contracts, reducing the lumen size and airflow to the lungs.

What is the purpose of cartilage in the trachea and bronchi?

It provides structural support to keep the airways open.

What is the primary site of gas exchange in the lungs?

The alveoli.

How does oxygen move from the alveoli to the blood?

It diffuses across the alveolar and capillary walls into the red blood cells.

What maintains a steep concentration gradient for gas exchange in the alveoli?

A network of capillaries surrounding each alveolus and ventilation through breathing.

What type of cells make up the walls of the alveoli?

Squamous epithelial cells, which are thin and flat.

What is the role of ventilation in the lungs?

It maintains a steep concentration gradient for gas exchange by bringing fresh air into the lungs.

What occurs during inhalation (inspiration)?

The volume of the thorax increases, causing a decrease in pressure and allowing air to flow into the lungs.

What is the countercurrent flow mechanism in fish?

It allows water and blood to flow in opposite directions, maximizing oxygen uptake.

How does the structure of alveoli contribute to gas exchange efficiency?

Their large number increases surface area, and their thin walls reduce diffusion distance.

What is the significance of a single layer of cells in alveoli and capillaries?

It minimizes the distance for gas diffusion, enhancing exchange efficiency.

What happens to carbon dioxide during gas exchange in the alveoli?

It diffuses from the blood into the alveoli to be exhaled.

What is the function of elastic fibers in the trachea?

They allow the trachea to stretch and recoil during breathing.

What is the role of the diaphragm in ventilation?

It contracts to increase thoracic volume during inhalation.

What is the relationship between metabolic rate and gas exchange requirements?

Higher metabolic rates increase oxygen demand, necessitating more efficient gas exchange systems.

How do root hair cells increase water and nutrient uptake?

Their long projections increase surface area for absorption.

What happens to air pressure in the thorax during inhalation?

Air pressure decreases, allowing air to flow into the lungs.

What muscle contracts during inhalation?

The diaphragm contracts and moves downwards.

What is the function of internal intercostal muscles during forced expiration?

They contract to pull the ribcage inwards and downwards, reducing thoracic volume.

What is tidal volume?

The amount of air inhaled and exhaled at rest.

What is residual volume?

The volume of air that remains in the lungs to prevent collapse.

How can breathing rate be determined from a spirometer graph?

By counting the number of peaks over a specific period of time.

What is the relationship between ventilation rate and oxygen uptake?

Oxygen uptake increases with an increase in ventilation rate.

How do fish ventilate their gills?

Fish swim with their mouths open to allow water to flow over the gills.

What is the function of the operculum in fish respiration?

It helps to regulate water flow over the gills during ventilation.

What structures make up the gills in fish?

Gill filaments covered in gill lamellae.

What is the tracheal system in insects?

A network of trachea and tracheoles that facilitate gas exchange.

What happens to gas exchange efficiency if the concentration gradient is not maintained?

Gas exchange efficiency decreases, affecting oxygen uptake.

What is the effect of exercise on ventilation rate?

Ventilation rate increases during exercise to meet higher oxygen demands.

What is the role of the buccal cavity in fish respiration?

It helps to create pressure changes that facilitate water flow over the gills.

What is the function of the gill filaments?

They increase the surface area for gas exchange in fish.

How does the diaphragm's movement affect thoracic volume?

When the diaphragm contracts, thoracic volume increases; when it relaxes, volume decreases.

What role do abdominal muscles play in respiration?

They pump new air in and old air out, aiding in gas exchange.

What is the effect of lactate on water potential in cells?

It lowers the water potential, causing water to move into abdominal cells by osmosis.

Which organisms typically have an open circulatory system?

Invertebrates like insects.

What is a closed circulatory system?

A system where the transport medium (blood) remains inside blood vessels.

Which organisms have a closed circulatory system?

All vertebrates and some invertebrates like annelid worms.

What is the difference between single and double closed circulatory systems?

Single systems pass blood through the heart once per cycle; double systems pass blood through the heart twice.

Give an example of an organism with a single closed circulatory system.

Fish.

What is the pulmonary circuit?

The circuit that carries blood from the heart to the lungs for gas exchange.

What are the main types of blood vessels?

Arteries, arterioles, capillaries, venules, and veins.

What is the function of capillaries?

They facilitate the exchange of gases, nutrients, and waste between blood and tissues.

What are the adaptations for gas exchange in fish?

Gills, which provide a large surface area and maintain a concentration gradient through countercurrent flow.

What adaptations increase the surface area in exchange surfaces?

Projections like root hair cells and folded membranes.

Why do capillaries have a narrow diameter?

To slow down blood flow and maximize diffusion as red blood cells are squashed against the walls.

What is tissue fluid?

Fluid that surrounds tissues, formed from liquid forced out of capillaries.

What is hydrostatic pressure?

The pressure exerted by a liquid, important for tissue fluid formation.

What is oncotic pressure?

The tendency of water to move into the blood by osmosis, influenced by plasma proteins.

How does hydrostatic pressure affect tissue fluid formation?

High hydrostatic pressure forces water and small molecules out of capillaries to form tissue fluid.

What happens to large molecules in capillaries?

They remain in the blood as they are too large to be forced out.

How does the presence of plasma proteins affect water potential?

It lowers the water potential of blood, increasing oncotic pressure.

What is the role of the heart in circulatory systems?

It acts as a pump to move the transport medium (blood or haemolymph) throughout the body.

What is the significance of a steep concentration gradient?

It enhances the efficiency of gas exchange and nutrient transport.

How do capillaries facilitate the movement of small molecules?

They have small gaps between endothelial cells that allow diffusion.

What is the relationship between hydrostatic and oncotic pressure in capillaries?

Hydrostatic pressure must be higher than oncotic pressure for tissue fluid to form.

What is the advantage of tissue fluid for cells?

It allows for the exchange of nutrients and waste products between blood and cells.

What happens to the volume of liquid in tracheoles during respiration?

It decreases due to osmosis as water moves into abdominal cells.

What happens to water potential in the blood when liquid is forced out of capillaries?

It lowers, resulting in higher oncotic pressure.

What is the net movement of liquid at the venule end of capillaries?

Liquid moves back into the capillaries by osmosis.

What happens to the final parts of tissue fluid?

They are absorbed into the lymphatic system and called lymph.

What type of muscle is the cardiac muscle?

Myogenic, meaning it automatically contracts and relaxes without fatigue.

What do coronary arteries supply to the heart muscle?

Oxygenated blood for aerobic respiration.

What is the function of pericardial membranes?

They prevent the heart from filling and swelling with blood.

Why does the left ventricle have a thicker muscular wall?

To contract with more force and pump blood at higher pressure to the body.

Why does the right ventricle have thinner cardiac muscle?

It pumps blood to the lungs at lower pressure and does not need as much force.

What is the purpose of the atria in the heart?

To push blood into the ventricles, which is a short distance and requires less force.

What are the three key stages of the cardiac cycle?

Diastole, atrial systole, and ventricular systole.

What occurs during diastole?

Both atria and ventricles relax, allowing blood to flow into the atria.

What happens during atrial systole?

The atria contract, increasing pressure and forcing blood into the ventricles.

What occurs during ventricular systole?

The ventricles contract, closing the atrioventricular valves and opening the semilunar valves.

What is cardiac output?

The volume of blood leaving one ventricle in one minute, calculated as heart rate times stroke volume.

What is the role of the sinoatrial node (SAN)?

It acts as the pacemaker, releasing a wave of depolarization across the atria.

What does the atrioventricular node (AVN) do?

It releases a wave of depolarization after receiving the signal from the SAN.

What is the bundle of His?

A conductive pathway that carries the depolarization wave from the AVN to the ventricles.

What are Purkinje fibers?

Fibers that branch into the walls of the ventricles to spread the depolarization wave.

What prevents the depolarization wave from spreading directly from the atria to the ventricles?

A non-conductive layer between the atria and ventricles.