Control And Coordination In Organisms

•The movement of plants towards water is hydrotropism.

•The movement of plants towards gravity is known as geotropism.

•The movement of plants towards chemical stimulus is known as chemotropism.

•The movement of plants towards light is phototropism.

Stem shows negative geotropism because it shows its growth against the force of gravity.

This is a picture showing geotropism.

The growth of pollen tube towards the ovule is caused in response to a chemical stimulus i.e the chemicals released by the ovule during the time of fertilization.

This is a picture showing chemotropism. Growth of pollen tube Observed in response to chemicals secreted by ovule

The movement of plant in response to light is known as phototropism

This is a picture showing phototropism. Growth of stem in response to light.

In Thigmotropism, the word ‘thigmo’ means touch, hence the movement of plant part in response to touch is thigmotropism.

This is a picture showing the process of thigmotropism. Here, the stimulus is touch.

Cerebellum is involved in maintaining body postures and co-ordinating body movments.

31 pairs of nerves arise from the centre of spinal cord.

This is because hind brain has 3 parts. Cerebellum present on the dorsal side of pons, while medulla and pons are present on the ventral side.

Because the deficiency of iodine can cause the deficiency of thyroxine hormone.

•Adrenaline is secreted by adrenal gland.

•Auxin is a plant hormone.

•Insulin is a hormone secreted by pancreatic glands which metabolizes sugar.

•Adrenalin hormone also known as fight or flight hormone is secreted by the adrenal gland.

•Ovary produces two female sex Hormones which are Estrogen and Progesterone which are responsible for controlling the development of female sex organs and controlling the changes taking place in uterus during menstrual cycle respectively

•Pancreas contain Islets of Langerhans that synthesize insulin

Spinal cord originates from the posterior side of medulla.

•This hormone is secreted by the adrenal gland. Medulla part of this gland secretes adrenalin hormone, which is called fight or flight hormone.

•Insulin is secreted by the pancreas.

•Testosterone is secreted by the testis.

•Growth hormone is secreted by pituitary gland.

Testosterone is secreted by the male reproductive part testis, hence it is the male sex hormone.

The rest of the three glands – adrenal, testis and ovary occur as a pair in human body. Pituitary gland, also known as the master gland is only one in number.

Mimosa is the plant which shows thigmonesty.

The leaves of the plant folds up in response to a touch.

A picture showing response of mimosa plant.

A. Positive phototropism. The growth of shoot takes place in the direction of light, that is towards the stimulus. Hence, positive phototropism.

Picture showing positive and negative phototropism.

B. Positive geotropism. The stimulus in the case of geotropism is gravity. As the growth of roots is towards the earth, i.e. under the force of gravity. Hence, positive geotropism.

C. Chemotropism. The growth of pollen tube is in response to the chemicals released by the ovule during fertilization.

D. Hydrotropism. The movement of plant part in response to water is known as hydrotropism.

E. Thigmotropism. Movement of plant part in response to touch is known as thigmotropism.

Thermometry. The movement is caused due the loss of water in in the pulvinus part of the leaf. When we touch the leaves of the ‘mimosa’ plant, they fold up in response to the touch.

Nervous system and Endocrine system are the two systems of control and co-ordination in higher plants.

The three components of a nerve cell are:

1. Cell body-Made up cytoplasm and nucleus, Have lots of fibers stretching out known as nerve fibers

2. Dendrites- Perform the role of picking up the message that sets of chemical reaction

3. Axon-Performs the role of passing the message to next nerve cell

Cerebrum is the most important part of human brain as it performs so many functions like visual reception, auditory reception, muscular activities, etc.

Function performed by:

1. Cerebellum- It maintains the balance of body and postures.

2. Pons- It regulates the process of respiration

Pituitary gland, also known as the master gland is associated with the secretion of many different hormones. It consists of three different lobes, structurally. Growth hormone is secreted by the anterior lobe of pituitary gland. Under-secretion of growth hormone from childhood results in a disorder known as dwarfism while over-secretion causes dwarfism.

Picture showing gigantism and dwarfism.

Hormones are synthesized by specialized cells in the glands of human body. They are also known as chemical messengers because they act at a particular target site in the body. Endocrine glands pour their secretion into the blood, hence they are also known as ductless glands.

Pituitary gland is associated with the secretion of growth hormone. The anterior lobe of the pituiatary gland secretes many different hormones like FSH( Follicle stimulating hormone), LH (leutenising hormone), Prolectin and growth hormone.

Picture showing location of pituitary gland in human brain.

The disease caused by the deficiency of insulin hormone in the human body is diabetes. Insulin is secreted by the specialized cells of pancreatic glands known as Islets of langerhans. Insulin controls the blood sugar level in blood. Diabetes causes large amount of sugar level in the blood and urine. That is why, diabetic patients should take less amount of sugar in diet.

Diagram showing working pancreas in the body

(A) The root grows towards the stimulus, that is it responds under the force of gravity positively.

This phenomenon is known as positive geotropism.

(B) The stem shows growth in response to the light, that is towards the light. This phenomenon is known as positive phototropism.

(A) A stem grows in opposite direction to the stimulus of gravity, that is, gravitational force attracts the plant parts towards itself but the stem grows upwards, which means against the force of gravity. This is known as negative geotropism.

(B) The response of root towards light is in opposite direction,that is it grows downwards, towards the dark. Hence, the phenomenon is known as negative phototropism.

(A) Spinal cord is a cylindrical structure which originates from the posterior extension of medulla oblongata( a part of hind brain). Function- It contain nerve fibres which help in the transfer of information from spinal cord to brain (known as ascending nerves) and from brain to spinal cord(known as descending brain).

(B) Function of medulla- It controls various involuntary activities like breathing, heartbeat, peristalsis movement of alimentary canal, blood pressure.

It also controls the main centre of reflex action like coughing, sneezing, vomiting, etc.

(A)

(B) Functions of testosterone- To control the development of sex organs and secondary sexual characters like deeper voice, adam’s apple, moustache. They are also involved in the production of sperms.

Functions of ovary- The function of estrogen is to control the development of sex organs and secondary sexual characters like soft skin, mammary gland,etc. The function of progesterone is to maintain the changes in uterus during menstrual cycle and also the production of ova.

(A) the regions of hind brain:-

1. Medulla- It controls various involuntary activities like breathing, heartbeat, peristalsis movement of alimentary canal, blood pressure.

It also controls the main centre of reflex action like coughing, sneezing, vomiting, etc.

2. Cerebellum- It maintains the balance of body and postures.

3. Pons- It regulates the process of respiration

(B) The cerebrum has 4 lobes. Each lobe performs specific functions:

1. Occipital lobe- performs the function of visual reception (to see).

2. Temporal lobe- performs the function of auditory reception (to hear)

3. Parietal lobe- performs the function of reception of general smell, touch and temperature.

4. Frontal lobe- controls specific muscular activities like thought, speech and memory.

CNS stands for Central Nervous System. It includes brain and spinal cord.

(A) When a plant part gets moved in response to an external stimuli or directional stimuli, then it is known as tropism. If the growth of plant part is towards the stimulus then it is called positive tropism and when the growth is away from the stimulus, then it is called the negative tropism.

Example- Growth of stem towards the light is an example of positive phototropism. The plant part – stem grows in the response to light.

(B) There are 5 common types of tropism:

1. Phototropism- The movement of plant part in response to light is known as phototropism. The stimulus in this case is –light.

2. Hydrotropism- The movement of plants towards water is hydrotropism. The stimulus is water.

3. Geotropism- The movement of plants towards gravity is known as geotropism. The stimulus in geotropism is gravity.

4. Chemotropism- The movement of plants towards chemical stimulus is known as chemotropism. The stimulus is chemicals.

5 Thigmotropism- The movement of plants towards light is phototropism. The stimulus in thigmotropism is touch.

(C)

(A) The movement of plant part in response to light is known as phototropism.

Example- Growth of stem towards the light is an example of positive phototropism. The plant part – stem grows in the response to light.

(B) In plant, the stem shows positive phototropism because it grows in the direction of light. The stimulus in phototropism is light.

(C)

(A) Nerve cell is the structural and functional unit of nervous system.

Picture showing structure of nerve cell showing the parts of it.

(B) The part of nervous system that control the functions of the body without any need of our conscious, such as breathing, heartbeat and digestive processes, is known as autonomous nervous system.

Functions- It control and regulates the processes like breathing, sweating, digestion, heart rate.

(C) Somatic nervous system – a type of peripheral nervous system is also known as voluntary nervous system.

Example- Reflex action.

When we touch a hot pan. The afferent neuron take the information from body to the central nervous system. The brain processes the information. The efferent neurons then take the information from the brain to the body back in the form of muscle contraction, so that we can move our hand away from hot pan.

(A) Reflex action is the simplest form of response of nervous system. It is an automatic process that occurs when we touch a hot pan, cut or hand through knife, yawning, etc.

Example- When we touch a hot pan.

•The afferent neuron take the information from body to the central nervous system.

•The brain processes the information.

•The efferent neurons then take the information from the brain to the body back in the form of muscle contraction, so that we can move our hand away from hot pan.

Diagram showing reflex arc. Reflex arc is the neural pathway involved in reflex action.

(B)

(A)

(B) Hypothalamus gland controls the secretion of hormones of pituitary gland.

(c) When adrenaline hormone is secreted in large amount into the blood, it raises the heartbeat and blood-pressure, due to which more glucose go into the blood. Thus the glucose provides energy to fight back in a situation. This is why it is also known as emergency hormone.

(D) Goitre is the disease which occurs in adults due to deficiency of iodine in the diet.

The main symptom is the enlargement of the thyroid gland.

Diagram showing the disease of goitre. It is caused due to the deficiency of iodone.