Topic 5 - Co-ordination and Response in Humans and Flowering plants Flashcards
How can organisms respond to changes in their environment?
By using sensitivity, they can sense changes in their environment and then respond to the stimuli.
What is homeostasis?
The maintenance of a constant internal environment, e.g. water levels, body temperature
What three things are needed for a coordinated response?
A stimulus, receptor and an effector
What stimuli do plants respond to?
Gravity (Geotropism)
Water (Hydrotropism)
Light (Phototropism
How do roots and stems respond to gravity? What is their geotropic response?
Roots are positively geotropic; growing with gravity to ensure they grow directly downwards to get water and minerals.
Stems are negatively geotropic; growing against gravity to ensure they grow upwards towards light
How do roots and stems respond to light? What is their photopic response?
Roots are negatively phototropic; they grow away from light, ensuring they go into the soil and get nutrients and water
Stems are positively phototropic; they grow towards the light to ensure that they can carry out photosynthesis using light.
What is auxin? What does it do?
Auxin is a hormone in plants produced in the tips of shoots and roots, It affects growth.
Auxins will move to the shaded side; essentially, they ‘run away’ from light. The shaded side of the plant’s cells are encouraged to absorb more water and elongate by auxin, bending the plant towards the light.
In shoots, auxin prevents cell elongation and growth, and the cells on the opposite side, with no auxin, will grow more, and the root will bend down.
What are six differences between nervous and hormonal communication?
Type of message: N = Electrical H = Chemical
Transportation method: N = Through Nerve cells/ Neurones H = Through bloodstream
Speed: N = Quicker H = Slower
Length of response: N = Shorter H = Longer
Area of response: N = Localised H = Widespread
Effect: N = Permenant H = Revesible
What does the CNS consist of?
The central nervous system (CNS) consists of the brain and spinal cord, which are linked to sense organs by nerves.
Label these three nerves. What are their functions?
- Sensory: Carries signal from receptors (e.g. eyes) back to CNS
- Relay: Carries messages from one part of the CNS to another
- Motor: Carries signals from the CNS to the effectors
What are 4 differences in the structure of a motor neuron and sensory neuron?
- M = Long Axon S = Short Axon
- M = No Receptor S = Receptor
- M = Cell body terminal & has dendrites
S = Cell body as side & no dendrites - M = Many short dendrons S = One long dendron
How does the body respond rapidly to a stimulus?
The receptors in the sense organ send an electrical impulse through nerves into the CNS, which sends an electrical response through nerves out to the effector organ, resulting in a rapid response.
What is the role of neurotransmitters at synapses?
A synapse is the gap between one neuron and the next neuron, and the electrical impulse can’t cross the gap. So Chemical neurotransmitters bind to the impulse and diffuse across the synapse. They then bind to receptors on the next neuron, where the electrical signal can be carried on.
What is a reflex arc/action?
A reflex action is a way for the body to automatically and rapidly respond to a stimulus to minimise any further damage to the body. The action does not involve the brain.
Instead of the brain making the decision, the relay neuron in the spinal cord automatically sends the message, without the brain being needed to reduce time and minimise further damage.
What is the function of the eye? Label the diagram.
The function of the eye is to see and provide information to the brain, as well as being a receptor organ.
How does the eye focus on nearby objects?
The ciliary muscles contract, the suspensory ligaments relax/slack and therefore the lens becomes convex (rounder and thicker).
How does the eye focus on faraway objects?
The ciliary muscles relax/slack and the suspensory ligaments contract, pulling the lens into a less convex shape (thinner)
How does the eye respond to bright light?
The circular muscles in the iris contract, and the radial muscles relax, which constricts the pupil, narrowing the gap for light to come through. Therfore less light gets through and damage to the retina is avoided.
How does the eye respond to dim light?
The circular muscles in the iris will relax, the radial muscles will contract, and the pupil dilates. This widens the gap for light to come through, which allows more light in, increasing eyesight.
Where are the sources, what are the roles and effects of:
Adrenaline
Insulin
Testosterone
Progesterone
Oestrogen
Adrenaline - Produced in the adrenal glands. Its role is to prepare the body for fight or flight. It does this by increasing the heart rate and pumping more blood/oxygen to muscles.
Insulin - Produced in the pancreas by beta cells. Its role is to store glucose for later use as energy. It does this by moving glucose into cells.
Testosterone - Produced in the testicles. Its role is sexual development, sperm production and secondary sexual characteristics.
Progesterone - Produced in the ovaries. Its role is to prepare the body for pregnancy and look after the womb during pregnancy. It does this by thickening the womb lining and preparing the breasts for milk production after pregnancy etc….
Oestrogen - Produced in the ovaries. Maintains the reproductive system, e.g. menstrual cycle. Similar role to testosterone but for females.
What are the sources, roles and effects of:
ADH
FSH
LH
ADH - Anti-diuretic hormone, produced in the pituitary glands and controls the body’s water levels. This is achieved by making collecting ducts’ walls more permeable to water to absorb more water; if overhydrated, less ADH is produced.
FSH - Follicle-stimulating hormone. Produced in the pituitary gland. Its role is to ensure the male and female reproductive systems work. Stimulates egg growth and ovulation in women and sperm production in men.
LH - Luteinizing hormone. produced in the pituitary gland. Ensures the reproductive system is healthy. It triggers ovulation in females and testosterone production in males.
