biology Flashcards
3 adaptations of red blood cells
No nucleus, contains a red pigment called haemoglobin, and has a bi-concave disc shape
2 adaptations of nerve cell
branched endings, myelin sheath insulates the axon
Function of palisade cell
carry out photosynthesis
2 adaptations of a palisade cell
lots of chloroplasts, located at the top surface of the leaf
2 adaptations of a root hair cell
long projection, lots of mitochondria
What is diffusion?
The movement of particles from an area of high concentration to an area of low concentration.
3 factors affecting rate of diffusion
Concentration gradient, temperature, surface area
How is the villi adapted to exchange substances?
long and thin-increases surface area
one cell thick membrane-short diffusion pathway
good blood supply-maintains a steep concentration gradient
How are the lungs adapted for gas exchange?
alveoli-large surface area
moist membranes-increased rate of diffusion
one cell thick membranes- short diffusion pathway
good blood supply-maintains steep concentration gradient
How are fish gills adapted for efficient gas exchange?
large surface area for efficient diffusion
thin layer of cells-short diffusion pathway
good blood supply-maintains steep concentration gradient
What is osmosis?
diffusion of water from dilute solution to concentrated solution through a partially permeable membrane
example of osmosis in plants
water moving from soil into root hair cell
What is active transport?
movement of particles against a concentration gradient, dilute to concentrated solution- using energy from respiration
Why is active transport needed in plant roots?
concentration of mineral ions in soil is lower than inside root hair cells, the mineral ions must move against the concentration gradient to enter root hair cells
Purpose of active transport in small intestines
sugars can be absorbed when concentration of sugar in small intestine is lower than concentration of sugar in the blood
