Biology Part A 2 Flashcards
Define transpiration
Transpiration is the loss of water from a plant
What do phloem and xylem tubes do
Phloem tubes transports food
Xylem tubes take water up
What is the function of the heart
To pump blood around the body
From where does blood flow into and out of the heart from?
It flows in through the vena cava and the pulmonary vein and out of the aorta and the pulmonary artery
Name the three different types of blood vessel and their basic method of transportation
Veins: carry at low pressure - to the heart - large lumen - valves
Arteries: carry blood at high pressure - thick walls smaller lumen - from the heart - thick elastic walls
Capillaries: branch off from arteries - very small - carry blood close to every cell - supply food and oxygen - takes co2 - one cell thick walls -
How is a red blood cell adapted to maximise oxygen transportation
Doughnut shape gives a larger surface area for absorbing oxygen
No nucleus so more room to carry oxygen
What are the main characteristics of white blood cells and platelets
White blood cells can changes shape to attack microorganisms.
They also produce antibodies and antitoxins and they have a nucleus.
Platelets have no nucleus they clot wounds and lack of them can lead to excessive bleeding and bruising
What is a stent
Stents are tubes that are inserted inside arteries keeping them open to allow blood pass through.
Define homeostasis
Homeostasis is the maintenance of a constant internal environment
What are the six main things controlled by homeostasis
Body temperature Water content Blood sugar Ion content Carbon-dioxide - waste product Urea - waste product
How do hairs on the body help regulate temperature
When your too hot hairs lie flat and sweat is produced
When your too cold hairs stand up to trap an insulating layer of air
Kidneys basically act as filters to clean the blood.
What are the three main roles of the kidneys?
Removal of urea from the blood
Adjustment of ions in the blood
Adjustment of water content of the blood
What is a nephron and what are the two stages it goes through
A nephron is a filtration unit in the kidneys
The first stage is Ultrafiltration in which water, urea, ions and sugar are squeezed out of the blood in high pressure
Reabsorption is the next stage where. all the sugar is reabsorbed via active transport into the blood with sufficient ions and water are reabsorbed.
What do dialysis machines do?
They filter blood through a partially permeable barrier surrounded in dialysis fluid it’s permeable to things like ions and waste substances but not big molecules like proteins
Name pros and cons of a kidney transplant
Pros
No more need for constant dialysis treatment so no more risk of blood clots or infections
Cons
Can be rejected by the patients immune system
Immune suppressing drugs can lead to infection from other bacteria.
On a waiting list
