levels of organisation and cell structure Flashcards
how does active transport use its energy
Active transport uses energy to move substances against a concentration gradient.
how are protein carriers and enzymes alike
they are able to recognize a specific shape and select them from a mixture
Why is active transport specific
active transport is specific so that the cell can “choose” which molecules to absorb from its surroundings
do red blood cells have a nucleus
no
does the nucleus control the cells activities
yes
what is an organelle
A component of a cell with a specific function
what are examples of organelles
Nucleus, Mitochondria, Chloroplast
what is a tissue
A group of similar cells which together perform a particular function
what is an organ
A structure made up of a collection of tissues, which performs a particular function.
what is an organ system
A collection of several organs working together to perform a particular task
what is diffusion
the movement of particles from a place of high concentration to a place of low concentration
what are factors effecting diffusion
Concentration gradient
Temperature
Distance particles must travel
what speeds up diffusion
Large concentration gradient
Higher Temperature
Short distance
what is biological diffusion
Dissolved substances have to pass through the partially permeable cell membrane to get into or out of a cell
what is digestion
Digestion breaks down large food molecules into smaller molecules that can be easily absorbed.
what do the villi do
in the small intestine they increase the overall surface area for maximum absorption and have a very good blood supply to absorb the nutrients
where does the oxygen from inhaled air go
the oxygen diffuses through the lungs and into the bloodstream before then being transported throughout the body
how does carbon dioxide exit the body
diffuses from body tissue into the lungs and is then exhaled by the lungs
what are the alveoli
tiny air sacs at the end of the bronchioles in which gas exchange occurs
what are the alveoli’s adaptations that make gas exchange more efficient
very thin(only one cell thick), they are covered by a network of fine capillaries(enabling gases to pass directly between the lungs and bloodstream), they are moist(encouraging gas molecules to easily dissolve) and they have a large combined surface area(allowing large amounts of gases to be exchanged)
what is the placenta
an organ that develops in the uterus during pregnancy
what does the umbilical chord connect
it connects the placenta to the foetus
what does the umbilical chord allow to happen
it enables nutrients and oxygen to pass to the foetus via diffusion and waste substances to diffuse back the other way
what is a synapse
a junction between two neurones across which electrical signals must pass
what is osmosis
The diffusion of water molecules, down a water potential gradient and across a semi-permeable membrane
what are the sources of human stem cells
Sources of human stem cells for current treatment and research are from the umbilical cords of newborn babies and the embryos that are not used following IVF treatments
what is a hypotonic solution
less water in the cell than outside, so it draws water into the cell through osmosis till it becomes turgid.
what is an isotonic solution
same amount of water inside the cell as outside
what is a hypertonic solution
more water inside the cell than outside, so water exits the cell via osmosis till it becomes flaccid
what is a stem cell
a non-specialised cell
what are the advantages of stem cells
can adapt to become a completely new cell, they are renewable
what are the ethical and religious objections to stem cells
catholicism disagrees with the procedure of getting stem cells, and it is DNA taken from people
how have palisade mesophyll cells been adapted
they are packed with chloroplasts for maximum photosynthesis and have a large surface area to catch more sunlight
how has a root hair cell been adapted for absorption of water and mineral ions
has a large surface area which will help absorption of water and mineral ions
how have guard cells been adapted for gas exchange and control of water loss
They open and close to allow materials in and out of the cell
how have xylem cells been adapted
they have become strengthened by a substance called lignin
how have phloem adapted
sieve tubes used for transportation and the companion cells used for transportation of substances in the phloem requires energy
how have red blood cells adapted
they have no nucleus so that they can contain more haemoglobin which is a red protein that combines with oxygen
how have white blood cells adapted
they can change shape to get out the way of blood cells and get to the site of infection
how have nerve cells adapted
they have a long fibre so they can carry messages up and down the body over long distances
how have cells with microvilli adapted
they increase the cells surface area meaning there is more absorption of ingested food and water molecules
how have sperm cells adapted
lots of mitochondria for energy and a tail to swim towards the egg
