2. Structure and functions in living organisms - (h) Transport Flashcards
What is diffusion?
Passive net movement of particles down the concentration gradient (from region of high concentration to region of low concentration) until equilibrium
Why can unicellular organisms rely on diffusion for movement of substance in and out of cells?
- As Unicellular organisms are composed of a single cell, they have a larger surface area in relation to their volume, and hence have a large surface area to volume ratio
- With a large surface area to volume ratio, Unicellular organisms therefore have efficient rate of diffusion, allowing cell to rely solely on diffusion to transport necessary substances in and out of the cell
What are some common features of unicellular organisms?
- Thin Cell Walls
Thin cell walls (one cell thick) to minimise distance of diffusion, increasing the rate of diffusion - Large Surface Area to Volume Ratio
Unicellular organisms are commonly long, thin, flat or folded to increase surface area to volume ratio, increasing the rate of diffusion - Moist
Unicellular organisms have moist membranes to allow substances to diffuse easily
What is a transport system?
A system that provides a constant supply of necessary substances through a medium to cells via an exchange surface - e.g circulatory system
Why does multicellular organisms have to rely on a transport system?
- As Multicellular organisms are composed of more than one cell, they have a small surface area in relation to their volume, and hence have a small surface area to volume ratio
- With a small surface area to volume ratio, Multicellular organisms therefore have inefficient rate of diffusion, preventing cell to rely on diffusion to transport necessary substances in and out of the cell (rate of metabolism will exceed rate of exchange of vital materials and wastes)
- Hence, Multicellular organisms rely on transport systems to provide a constant supply of necessary substances through a medium to their cells via an exchange surface
What are some common features of transport systems?
- TUBES OR VESSELS
Tubes or vessels to carry necessary substances from one part of organism to another in a structured process - CLOSE CONTACT WITH CELLS
Transport system will have close contact with cells via exchange surface for efficient exchange of necessary substances - PUMPS
Transport system may have pumps to ensure a constant supply of necessary substances to cells - the heart acts as a pump to ensure the constant circulation of blood by which materials are transported by in the human circulatory system
What is the phloem?
Tube system that transports organic compounds (Sucrose and Amino acids) from Sources to Sinks via Translocation
What is source?
Where organic compounds are synthesised (photosynthetic tissue - leaves)
What is sinks?
Where organic compounds are delivered to for use or for storage (roots, fruits and seeds)
What is the xylem?
Tube system composed of dead cells (reinforced with Lignin) that transports Water through the plant via transpiration - evaporation of water from the surface of plant)
Describe the Xylem in Transporting Water and Mineral Ions from the Roots to Other Parts of the Plant:
- Water is transported throughout the plant via Xylem
- Water is heated into Water vapour by sunlight in Spongy Mesophyll, transpiring out of Stomata which are pores on the underside of leaves
- Loss of Water via transpiration creates negative pressure, causing transpiration pull of Water molecules up the Xylem to form a continuous transpiration stream
- As a result, more Water is absorbed by the roots of the plant via osmosis
What is the function of the xylem?
- Constant uptake and transport of Mineral ions in plant (e.g Nitrates as a source of Amino acid to build Protein)
- Maintaining turgidity of cells for plant growth
- Provide Water to Photosynthesising cells in for Photosynthesis
- Evaporative cooling of plant leaves to maintain optimum temperature for optimum enzyme activity
What is a red blood cell?
Transports Oxygen in Haemoglobin of cell from Lungs to respiring cells for aerobic respiration
What are white blood cells?
Composed of two types of cells - Phagocytes that engulf and digest pathogens, and Lymphocytes that produce antibodies to deactivate antigens of Bacteria
What are platelets?
Cell fragments involved in blood clotting
What is plasma?
Medium of transport that carries Carbon Dioxide, digested food, Urea, Hormones and Heat
What is the blood made of?
55% - Plasma
45% - Red and white blood cells and platelets
What is the role of plasma in transporting carbon dioxide?
Plasma transports waste Carbon Dioxide produced via aerobic respiration to the lungs for exhalation
What is the role of plasma in transporting digested food?
Plasma transports digested food to respiring cells for assimilation in the form of simple sugars (e.g glucose) and Amino acids
What is the role of plasma in transporting urea?
Plasma transports waste substances for removal out of the body - Plasma transports Urea from liver to the kidney for excretion
What is the role of plasma in transporting hormones?
Plasma transports Hormones produced by Endocrine glands to target organs to stimulate change
What is the role of plasma in transporting heat energy?
As Plasma is mainly composed of Water which possesses high specific heat capacity, this allows Plasma to maintain a constant body temperature optimum for enzyme activity for metabolic reactions to occur (optimum body temperature is 37°C)
Name 5 of the adaptations red blood cells have made?
- haemoglobin
- no nucleus
- small and flexible
- thin cell membrane
- biconcave (disc shape)
How does an increase in haemoglobin make the red blood cell more effective?
Red blood cells contain Haemoglobin that combines with Oxygen to form Oxyhemoglobin to transport Oxygen to respiring cells
How does no nucleus make the red blood cell more effective?
Red blood cells do not have a Nucleus to allow more space for Haemoglobin to transport Oxygen to respiring cells
How does the red blood cell being small and flexible make the red blood cell more effective?
Red blood cells are small and flexible to squeeze through narrow capillaries and blood vessels for efficient transport
How does a thin cell membrane effect a red blood cell?
Red blood cells have thin cell membrane (one cell thick) to minimise distance of diffusion of Oxygen molecules, allowing efficient diffusion and transport of Oxygen to respiring cells
How does the red blood cell being a biconcave shape effect the red blood cell?
Red blood cells have flattened disc shape to increase surface area to volume ratio for diffusion of Oxygen, allowing efficient diffusion and transport of Oxygen to respiring cells
What are phagocytes?
White blood cell that engulfs and secretes digestive enzymes onto pathogens to remove them from the body
What are some adaptations of phagocytes?
SENSITIVE CELL SURFACE MEMBRANE
Phagocytes have sensitive cell surface membrane that detects and locates pathogens via chemical produced
DIGESTIVE ENZYMES IN CYTOPLASM
Phagocytes have digestive enzymes in cytoplasm to digestion and remove pathogen from body once engulfed
IRREGULAR SHAPED NUCLEUS
Phagocytes have irregularly shaped Nucleus to squeeze through narrow gaps in capillary walls, allowing them to digest and remove pathogen quickly
What are lymphocytes?
White blood cell that produces antibodies to deactivate antigens on the surface of pathogens, additionally producing memory cells that remain in immune system for quick response to same antigens
What is one adaption of lymphocytes?
LARGE NUCLEUS
Lymphocytes have large Nucleus containing multiple copies of DNA to produce antibodies in large amounts, preventing spread of diseases and infections
How do the lymphocytes respond to disease in the immune system?
- When Pathogen is detected, Lymphocyte will split into two cells
- One cell will produce Antibodies that will deactivate Antigens of Pathogens
- Other cell will be memory cell that remains in immune system so if same Pathogen is detected, same Antibodies can be produced in larger quantities quickly
How do the phagocytes respond to disease in the immune system?
- Phagocytes has sensitive cell surface membrane detects and locates Pathogen via chemicals produced
- Once Pathogen is encountered, they will engulf and release digestive enzymes to digest and Pathogen
- Pathogen is removed from the body
What is the heart?
Chambered muscle organ that is composed of Cardiac muscle, and is myogenic to initiate contractions to pump blood around the body
What is the atrio ventricular valve and what is the semilunar valve?
ATRIO VENTRICULAR VALVE: Valve that prevents the backflow of blood from Ventricle to Atrium
SEMILUNAR VALVE: Valve that prevents the backflow of blood from Artery to Ventricle
Describe the structure of the heart and how it works:
- Deoxygenated blood from respiring cells are carried by the Vena Cava to the Right Atrium
- Right Atrium will contract to increase pressure, pushing blood into Right Ventricle through Atrioventricular Valve
- Atrioventricular Valve closes to prevent backflow of blood from Ventricle to Atrium
- Right Ventricle will contract to increase pressure, causing blood to be carried out via Pulmonary Artery to be Oxygenated at the Lungs through the Semilunar Valve
- Semilunar Valve closes to prevent backflow of blood from Artery to Ventricle
- Pulmonary Vein carries Oxygenated blood from Lungs to the Left Atrium
- Left Atrium will contract to increase pressure, pushing blood into Left Ventricle through Atrioventricular Valve
- Atrioventricular Valve closes to prevent backflow of blood from Ventricle to Atrium
- Left Ventricle will contract to increase pressure, causing Oxygenated blood to be carried out via Aorta to respiring cells around the body
What is heart rate?
Rate at which the Heart beats (measured in beats per minute)
What is adrenaline?
Hormone produced by Adrenal Gland that increases heart rate for ‘fight or flight’ response
How does heart rate change during exercise?
- During exercise, more energy is needed via respiration to allow muscle contractions to occur to facilitate movement
- Hence, heart rate will increase to allow more Oxygen transport in blood to respiring cells for movement to occur
- If energy demand exceeds Oxygen intake, energy may be produced via anaerobic respiration, producing Lactic acid as a waste product
- After exercise, heart rate continues to increase as extra Oxygen is needed to break down the Lactic acid produced - Oxygen debt
How does adrenaline effect heart rate?
- During times of fear or stress, Adrenaline is produced by Adrenal glands and secreted into the bloodstream
- As a result, Liver cells convert Glycogen into Glucose to increase blood glucose levels
- Additionally, breathing and heart rate increases to increase blood flow
- Hence, the increase in breathing and heart rate allows more Glucose and Oxygen to be transported in the bloodstream to respiring cells for ‘fight or flight’ response to occur
What is coronary heart disease?
Blockage of Coronary Artery by Fat globules (forming plaques), causing insufficient Oxygen transport in blood leading to increased anaerobic respiration (due to lack of Oxygen)
Why is an increased anaerobic respiration bad?
Increase in anaerobic respiration causes build-up of Lactic acid which creates acidic environment for enzymes to denature, hence causing strokes
What factors can increase the risk of coronary heart disease?
- poor diet
- stress
- smoking
Explain how a poor diet can lead to CHD:
Diets rich in Saturated Fats, Salts and Alcohol increases the presence of Cholesterol in diet, increasing the risk of Coronary Heart Disease (CHD)
Explain how stress can lead to CHD:
Stress stimulates the secretion of Hormones that increases blood pressure, therefore increasing the risk of the buildup of Fatty plaques to cause Coronary Heart Disease (CHD)
Explain how smoking can lead to CHD:
Nicotine in cigarettes causes vasoconstriction - the narrowing of blood vessels, increasing the risk of the buildup of Fatty plaques to cause Coronary Heart Disease (CHD)
What is the Structure of Arteries and how does this Relate to their Function?
- Transports Oxygenated blood away from the Heart (excluding Pulmonary Artery)
- Thick muscular walls to withstand high pressure
- Narrow lumen to maintain high pressure to pump blood around the body
What is the Structure of veins and how does this Relate to their Function?
- Transports Deoxygenated blood towards the Heart (excluding the Pulmonary Vein)
- Thin walls to allow Skeletal muscle to exert pressure on Vein
- Wide lumen to transport large volume of blood
- Valves to prevent the backflow of blood under low pressure
What is the Structure of capillaries and how does this Relate to their Function?
- Facilitates material exchange between cells - e.g., gas exchange
- Thin walls (one cell thick) that are porous and permeable for efficient material exchange via diffusion
- Narrow lumen to fit between cells for extensive branching, which increases surface area to volume ratio for efficient material exchange via diffusion
What is the circulatory systems?
System composed of Heart, blood vessels and blood that delivers nutrients and other essential materials to cells, whilst removing waste products
