B4 - Organising Animals And Plants Flashcards
Components of the blood and functions?
- Red blood cells - carry oxygen
- White blood cells - protects body against infection and foreign pathogens
- Platelets - small fragments of cells. Help blood clot as a wound.
- Plasma - yellow liquid that has blood cells suspended in it and transports proteins and other substances around the body.
How are red blood cells adapted?
- biconcave disc shape which increases SA:V ratio for diffusion of oxygen
- packed with haemoglobin that binds to oxygen
- no nucleus to make more space for haemoglobin
How does the blood clot?
Enzymes help convert fibrinogen to fibrin, which produces a network of protein fibres that captures blood cells and forms a clot to stop excessive bleeding. This dries and hardens to form a scab which stops bacteria entering the body
What does the plasma carry? And where does it take them?
- Waste CO2 produced by the cells -> lungs
- Urea formed in liver from break down of proteins -> kidneys
- Small soluble products of digestion -> from small intestine to cells
3 main types of blood vessels?
Arteries, veins, capillaries
What direction to arteries carry blood?
Away from heart and to organs. (Oxygenated)
What direction do veins carry blood?
Towards the heart away from the organs (deoxygenated blood)
Capillaries allow…
The diffusion of substances such as oxygen and glucose into the cells, and substances such as CO2 to diffuse into blood.
Define a double circulatory system?
One system carries blood from the heart to the lungs and back. One system carries blood from the heart all around the body and back.
Function of stents?
Keep narrowed or blocked arteries open
Function of statins?
Reduce cholesterol levels in blood, reducing risk of coronary heart disease.
What is a natural pacemaker?
A group of cells in the right atrium that form a natural pacemaker
Adaptions of alveoli?
- has a good blood supply which maintains a steep concentration gradient for diffusion by removing CO2 from the lungs and bringing in lots of O2
- rounded shape providing for a large surface area for diffusion (lungs contain many alveoli –> large surface area)
- thin alveolus wall (one cell thick) providing a short diffusion distance
- moist walls allow gases to diffuse and cross membrane more easily
Examples of plant organ systems?
Roots, stem and leaves form an organ system
Define translocation?
The movement of dissolved sugars from leaves to the rest of the plant.
Why is transport in plants so important? (4)
- all cells need glucose for respiration
- minerals are needed for production of proteins and molecules within a cell
- need water for photosynthesis
- needs water to remain turgid
Define transpiration?
The loss of water vapour from the leaves of a plant by evaporation through the stomata
Through what is water lost in plants? Why?
The stomata as they open to allow CO2 to enter
What controls water loss and gas exchange in a plant?
The stomata and guard cells
The size of the opening of the stomata is controlled by…..
Guard cells
How does the transpiration stream work?
Due to the loss of water by evaporation from the surface of the leaves, more is pulled up through the xylem to replace it.
This constant movement of water molecules through the xylem from the roots to leaves is known as the transpiration stream.
Factors that increase the rate of photosynthesis?
- Humidity
- CO2 concentration
- Temperature
- Light intensity
- Air flow
Transpiration is more rapid in what conditions?
Dry/windy/hot
What does the pulmonary artery do?
Carries deoxygenated blood from the heart to the lungs
What does the aorta do?
Carries oxygenated blood from the heart to the rest of the body
What does the pulmonary vein do?
Carries oxygenated blood from the lungs to the heart
What does the Vena cava do?
Carries deoxygenated blood from the rest of the body into the heart.
Adaptations of villi?
- Supplied with a network of blood capillaries which maintain a steep concentration gradient to transport glucose and amino acids away from the small intestine into the blood
- Microvilli on the surface of villi increasing the surface area for diffusion
- Walls of villus is one cell thick (very thin) providing a short diffusion distance
How do stents work?
- A narrow tube is threaded up through the groin up to the blocked vessel
- A tiny balloon is then inflated
- The balloon pushes the metal or plastic stent against the wall of the artery, increasing the width of the lumen
- The balloon and tube are then removed
Describes the events that can lead up to a heart attack (+ coronary heart disease) (6 marks)
The effect of a narrowed lumen in a coronary artery is reduced blood flow to the heart.
If a coronary artery becomes partially/ completely blocked by these fatty deposits, it loses its elasticity and cannot stretch to accommodate the blood which is being forced through every time the heart contracts.
This reduces the flow of blood through the arteries resulting in a lack of oxygen for the heart muscle - therefore heart muscle cannot undergo aerobic respiration.
Partial blockage of the coronary arteries creates a restored blood flow to the cardiac muscle cells and results in severe chest pains called angina.
Complete blockages means cells in that area of the heart will not be able to reposted aerobically, leading to heart attack
What is Coronary Heart Disease (CHD)?
Layers of fatty material build up inside the coronary arteries, formed from cholesterol
What is cholesterol important for?
- Making bike
- Part of cell membranes
- Synthesis of steroid hormones
