B4 - Organising plants and animals Flashcards
name four main components of blood
red blood cells, white blood cells, plasma, platelets
function of platelets
form blood clots - prevent loss of blood and stop wounds being infected
why is human circulatory system a double circulatory system
- blood passes through the heart twice for every circuit around the body
- deoxygenated blood is pumped from right side of heart to the lungs
- oxygenated blood that returns is pumped from left side to the rest of the body
how does structure of artery help with its function
- carries blood away from heart under high pressure
- small lumen
- thick elasticated walls that can stretch - thick muscle to withstand the pressure
how does structure of vein relate to its function
- carries blood back to heart at low pressure
- thinner walls because not so much pressure
- has valves to prevent backflow of blood
how does structure of capillary relate to its function
- carries blood through organs and tissues
- one cell thick walls to shorten diffusion distance
list structures air passes through when breathing in
mouth/nose > trachea > bronchi > bronchioles > alveoli
what is the function of red blood cells
bind to oxygen and transport it around the body
what is the function of white blood cells
defend body against pathogens
what is the function of the plasma
transports blood cells and substances around the body
why is a leaf an organ
there are many tissues inside the leaf which work together to perform a function (photosynthesis)
how is the upper epidermis adapted for its function
- single layer of transparent cells allow light to pass through
- cells secrete a waxy substance that makes leaves waterproof (waxy cuticle)
how is the palisade mesophyll adapted for its function
tightly packed cells with lots of chloroplasts to absorb as much light as possible for photosynthesis
how is the spongy mesophyll adapted for its function
air spaces increase the surface area and allow gases to diffuse quickly
what is the function of the guard cells
to control the opening and closing of the stomata
what is the function of the xylem
transport water and mineral ions from the roots to the rest of the plant
give three adaptations of the xylem
- made of dead cells
- no end wall between cells
- walls strengthened by a chemical called lignin to withstand the pressure of the water
what is the function of the phloem
transport dissolved sugars from the leaves to the rest of the plant
what is the purpose of translocation
transport dissolved sugars from the leaves to other parts of the plant for respiration, growth, and storage
define the term transpiration
movement of water from the roots to the leaves through the xylem
what is the purpose of transpiration
- provide water to keep cells turgid
- provide water to cells for photosynthesis
- transport mineral ions to leaves
name four factors that affect the rate of transpiration
temperature, light intensity, humidity, and wind speed
what effect does temperature have of transpiration
higher temperatures increase the rate of transpiration
what effect does humidity have of transpiration
higher levels of humidity decreases the rate of transpiration
why does increased light intensity increase the rate of transpiration
stomata open wider to let more carbon dioxide into the leaf for photosynthesis
what is the function of the stomata
allow diffusion of gases into and out of the plant
where are most stomata found
underside of leaves
what is the advantage of the plant of having a high number of stomata at this location
reduces the amount of water loss through evaporation
