Describe how the nervous system enables the body to respond to stimuli. Include in your answer the roles of sensory neurons, motor neurons, and synapses in transmitting signals.
the stimuli are detected by receptors(in the skin or eyes)
the sensory neurones transmit electrical impulses to the CNS
the brain processes the information and sends a response via motor neurones
motor neurones carry carry impulses to effectors(muscles, glands)
synapses transmit electrical impulses via neurotransmitters
reflex arcs can bypass the brain for rapid responses(involuntary)
Explain how cells become specialised for specific functions. Include in your answer the roles of root hair cells, sperm cells, and red blood cells, and how their structure relates to their function.
Root hair cells are specialised for water and mineral absorption
Sperm cells have a long tail for movement, mitochondria for energy and an acrosome for fertilising the egg
Red blood cells are biconcave to increase surface area and lack a nucleus to carry more haemoglobin
Specialised cells have structures adapted to their functions
Specialisation occurs during development
Explain how the structure of alveoli is adapted for efficientgas exchange.
Alveoli have a large SA due to their spherical shape which increases the area for gas exchange
Alveoli are one cell thick, providing a short diffusion distance for gases
Alveoli are surrounded by a network of capillaries, allowing for a rich blood supply and maintaining a concentration gradient
moist walls allowing gases to diffuse more easily
large SA ensures that oxygen can be absorbed into the bloodstream and carbon dioxide can be expelled
Describe the process of osmosis in plant cells and explain how it affects the cell's turgidity? PART 1
Osmosis is the movement of water molecules from a high concentration to a low concentration across a semi-permeable membrane
In plant cells, water enters the cell through the cell membrane by osmosis when the surrounding solution is hypotonic(low conc of solutes than cell)
As water enters, the cell vacuole fills up, and the cells swells