Сборник текстов на казахском, русском, английском языках для формирования навыков по видам речевой деятельности обучающихся уровней среднего образования

Fig 2: Gram positive bacteria Fig 2: Gram negative bacteria

Gram negative enteric bacilli play an important role in the contamination of food. Hence they are the main causative agents of intestinal infection. Gram negative family includes Shigella, Salmonella, Proteus, Klebsiella,Escherichia,Enterobacter etc. Usually four tests are used for differentiation of the various members of Enterobactericeae. They are Indole test,Methyl red test, Voges proskauer test and Citrate test; collectively known as IMViC series of reactions.

Animals move in search of food, shelter, water, and many other purposes.

Learn about the different types of movement in animals such as:
Muscular movement

Invertebrate movement

Also learn about the skeletal system in animals, which helps in support and movement of animals.
All living organisms show movement in different ways. Though plants are

fixed to the ground, they show movement too.

Geotropism

Phototropism

Hydrotropism

Thigmotropism

Nastic movements

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Coordination And Regulation In Living Organisms
All the living organisms (plants and animals) respond and react to changes in the environment around them. The changes in the environment to which the organisms respond and react are called stimuli (singular of stimuli is stimulus). The living organisms show response to stimuli such as light, heat, cold, sound, smell, taste, touch, pressure, pain, water, and force of gravity, etc.

The response of organisms to a stimulus is usually in the form of some movement of their body part. For example, if a man touches a very hot utensil accidentally, he quickly pulls his hand away from the hot utensil. Here, heat is the stimulus and the man reacts by moving his hand away from the hot utensil. Similarly, when the sun is bright, we close our eyes. In this case, light is the stimulus and we reacting by closing the eyes.

The animals can react to stimuli in many different ways because they have a nervous system and an endocrine system involving hormones. The plants, however, react to stimuli in a very limited way. This is because the plants do not have a nervous system like the animals have. The plants use only the hormones for producing reaction to external stimuli.

From all the above examples we conclude that when a stimulus acts on our body, then we react (or 1 respond) in a manner which is in the best interest of our body. The reaction (or response) which we give to the stimulus involves many organs of our body.
It is, therefore, necessary that all the concerned organs should work with one another in a systematic manner so as to produce the required reaction. In other words, the various organs should co-operate with one another to provide proper reaction to the stimulus.
The working together of the various organs of an organism in a systematic manner so as to produce a proper response to the stimulus is called coordination. We will now discuss the control and coordination in plants, animals and human beings, one by one. Let us start with control and coordination in plants.
Control and Coordination in Plants:

The plants do not have a nervous system and sense organs like eyes, ears, or nose, etc., like the animals, but they can still sense things. The plants can sense the presence of stimuli like light, gravity, chemicals, water, and touch, etc., and respond to them. The plants can sense things like light, gravity, chemicals, water, and touch, etc., by the action of hormones in them.

The stimuli like light, gravity, chemicals, water, and touch, etc., are called environmental changes. So, we can also say that the plants coordinate their behaviour against environmental changes by using hormones. The hormones in plants do not act the same way as in animals.
The hormones in plants coordinate their behaviour by affecting the growth of a plant. And the effect on growth of the plant can result in the movement of a part of the plant like shoot (stem) or root, etc.
Animals use both nervous system and hormones for coordination of their activities. Plants have no nervous system, so plants use only hormones for coordination. Thus, the reaction (or response) of plants to different stimuli like light, gravity, chemical substances, water, and touch etc., is due to the effect of hormones.
Control And Coordination In Living Organisms – Ii : Brief And Long Answers Tropism
The movement of curvature of plants in the direction of stimuli is known as tropism. Phototropism : When illuminated by a unidirectional light, the response of agrowing plant by bending towards that light is called phototropism.

Geotropism : The downward movement of the roots of the plants, for fixation and absorption, as a response to the gravitational force is called geotropism.

Examples :

The leaves of Mimosa (touch-me-not) are sensitive to touch. They droop when touched.

All insectivorous plants bend down or curl up when touched by insects.

A sunflower plant bends towards the sun.

Of the above examples, (i) and (ii) are examples of thigmonastic response and

3. 
   is an example of photonastic response.
   

Distinguish between tropic movement and nastic movement.

Photoperiodism.

Plants respond to photoperiodic stimulus by a 531omplimenta pigment present in them called phytochrome.

All multicellular organisms, except porifera, have well-developed nervous system.

Hydra and other cnidarians possess nerve cells which form a nerve net in the body.

In invertebrates, the nerve net condenses into nerve mass called ‘ganglion’.

Insects have a bilobed nerve mass (brain), nerve cord and nerve ganglia.

Higher organisms possess sensory organs (receptors) related to light, hearing, taste, touch and smell.

Hormones also play an important role in control and coordination in animals.

In vertebrates there is a successive development of nervous system.

The nervous system of human beings is highly developed.

Cerebrum is the most complex and 533omplimenta part of the brain.

It has sensory area to receive impulse from the sense organs and motor area to send impulse to muscles and effector organs.

The frontal lobe possesses centres for voluntary muscular activities.

Parietal lobe possesses the centres for temperature control, smell and touch.

Temporal lobe possesses the centres for auditory and olfactory reception.

Occipital lobe possesses the centres for visual reception.

Mid -Brain is a part of the brain stem and possesses the regions for visual reception, auditory reception and touch.

Cerebellum is situated on the posterior side of the fore-brain and it controls the rhythmic movement of muscles, body balance and posture.

Spinal cord is a cylindrical structure.

It is the posterior extension of of medulla oblongata.

There are 31 pairs of spinal nerves arising from the spinal cord.

These nerves connect various organs of the body to the brain.

They help in the conduction of impulses from brain to organs and from organs to brain.

An unconscious and involuntary response of effectors to the stimulus is called reflex action.

rest.

The system which is responsible for the intervention in the activities of the organs located in the body cavity without the awareness of brain is called autonomous nervous system.

The involuntary actions of the body are controlled and regulated by the coordination of these two systems.

For example: If the sympathetic system increases the heartbeats abnormally, the parasympathetic system decreases it and brings it back to normal.

They are specific chemical messengers.

Generally the origin and the target area of hormones are different.

They are directly poured into the blood (from the gland) and carried by blood