EXERCISES
How does phototropism occur in plants?
Why do roots grow towards the soil ? Explain with three points
Explain the function of two growth inhibitors in plants.
In what way auxin is involved in the process of apical dominance ?
What is the name of the gap between the two neurons ?
What is the function of receptors in our body? What will be the conditions
if the receptor are not properly working?
How do the reflex actions differ from the involuntary actions?
Explain the functions of any three hormones in human being
please help me
I will mark the answer as brainlist
Answers
(a) Phototropism is the growth of an organism in response to a light stimulus. ... The cells on the plant that are farthest from the light have a chemical called auxin that reacts when phototropism occurs. This causes the plant to have elongated cells on the furthest side from the light.
(b)The growth of the root towards the soil is a graviotropic or hydrotropic movement. in search of water and minerals. to hold the soil tightly. ... Several hormones like auxins, ethylene, and cytokines play role in growth of root.
(c)Plant Growth Promoters – They promote cell division, cell enlargement, flowering, fruiting and seed formation. Examples are auxins, gibberellins and cytokinins. Plant Growth Inhibitors – These chemicals inhibit growth and promote dormancy and abscission in plants. An example is an abscisic acid.
(d)The apical bud produces a hormone, auxin, (IAA) that inhibits growth of the lateral buds further down on the stem towards the axillary bud. ... When the apical bud is removed, the lowered IAA concentration allows the lateral buds to grow and produce new shoots, which compete to become the lead growth.
(e)Synapse, also called neuronal junction, the site of transmission of electric nerve impulses between two nerve cells (neurons) or between a neuron and a gland or muscle cell (effector). A synaptic connection between a neuron and a muscle cell is called a neuromuscular junction.
(f)Receptors are present over all parts of the body, for example, in skin, eye, nose, tongue etc. They detect the signals and then send them to the brain in the form of electrical signals. If receptors are damaged, they will not detect the input, leading to harm for our body in a dangerous situation.
(g)The receptors in our body collect information about changes in the environment around us in the form of stimuli. ... When receptors do not work properly, the environmental stimuli are not able to create nerve impulses and body does not respond.
(h)
Involuntary action is the set of muscle movement which do not require thinking. But it is controlled by brain for example beating of heart beat. While on the other hand, the reflex action is rapid and spontaneous action in response to any stimulus which doesn't involve brain.
(i)Hormone Secreting gland(s) Function
glucagon pancreas helps to increase levels of blood glucose
insulin pancreas helps to reduce your blood glucose levels
luteinizing hormone (LH) pituitary controls estrogen and testosterone production as well as ovulation
melatonin pineal controls sleep and wake cycles