How living things respond to its environment
This is not just about the organism responding to stimuli but the respond to growth and movement within the cell of an organism
One of the characteristics of a living thing is responding to stimuli. All living thing are capable of responding to internal and external stimuli. The ability to do this is called irritability or sensitivity. Through this means, plants and animals are able to detect and respond to changes in their environment.
So irritability is one of the basic characteristics of living organisms.
TYPES OF RESPONSES
Animals responds to irritability quicker than plan does to external changes to or in their environment. Here it is worthy of note that only a part of plant respond to stimuli while the animals responds through their whole body.
iii. Tropic movements
TAXIS OR TACTIC MOVEMENTS
What is taxis or tactic movement?
Taxis or tactic movement/responses is a type of directional responses or movement in which a whole organism moves from one place to another in response to external stimuli such as light, temperature, water and certain chemicals.
Examples of tactic movements are
THERMOTAXIS TYPE OF RESPONSE:
this is the movement of organisms in response to temperature change or heat. Example is a snail moving from hot region to a cold region. And this is known as negative Thermotaxis
PHOTOTAXIS TYPE OF RESPONSE:
Phototaxis is the movement in response to light stimuli by organisms. It is the source of light to organisms. E.g. Euglena moving away from sunlight.
HYDROTAXIS TYPE OF RESPONSE:
Hydrotaxis is the response of the whole organism in response to water or humidity, example is the woodlouse moving towards areas of high humidity
CHEMOTAXIS TYPE OF RESPONSE:
Chemotaxis is the movement of organism in response to a chemical stimuli. Example is Amoeba and Paramecium moving away from hot water
NASTISM OR NASTIC MOVEMENTS
WHAT IS NASTISM?
WHAT IS NASTIC MOVEMENTS?
Nastism is a type of response in which a part of a plant moves in a non-directional stimuli such as changes in light density,
The respond movement is also non-directional. Examples of Nastic movements are as follows
i. Closing of the morning glory flower when the light intensity is low
ii. Petals of sun flower which opens in the light and closes in the dark
iii. The folding of the leaflets of the Mimosa plant when it is touches
iv. The closing of the leaflets of the Flamboyant tree. That is sleeping movement due to low light intensity.
TROPISM OR TROPIC MOVEMENTS
WHAT IS TROPISM?
Tropism is a type of response in which a part of a plant moves in response to a directional stimulus. The direction of the movement is related to that of the stimulus and it is positive if the plant part grows towards the stimulus and it is negative if the plant part grows away from the stimulus.
Tropism are very slow growth movement. They are named according to the stimuli, e.g. Phototropism which is a response to light and Hydrotropism which is response to water.
EXAMPLES OF TROPIC RESPONSES
Names of stimuli, names of response and examples of it
1. LIGHT==phototropism type of response====examples are how the shoots of plants bends towards light which is known as =positive phototropic.. while the roots of plants moves away from light also known as negative phototropic
2. GRAVITY==GEOTROPISM== examples are the shoots of green plants bends away from gravity which also known as negatively Geotropic=while roots bends towards gravity also known as positively Geotropic
3. WATER==Hydrotropism==example is how the roots of plants move towards moisture which is known as positively Hydrotropic= while the shoot bends away from moisture also known as negatively Hydrotropic
4. TOUCH==THIGMOTROPISM==example is how the tendrils of a climbing plant twine around a support as a positive response to touch== while the roots grows away from touch as a negative response
The differences between TROPIC AND nastic movements. These are the major difference between tropic and nastic movement and response to either internal or external stimuli. It cannot be said enough here about the difference between tropic and nastic movement in response to stimuli in living organisms; here I am going to treat a little of the varied difference between tropic and nastic movement
The question is how do we recognize a tropic movement? The following are the various ways to recognize a tropic movement
1. Tropic movement involves growth movement
2. Topic movement involves responding to unilateral stimuli
3. In tropic movement, response is very slow
4. Growth in tropic movement is irreversible
5. Tropic movement is not due to turgor
6. Tropic movement is a directional, positive or negative response to stimuli
Here are the various ways or major
differences that makes nastic movement different from tropic movement.
They are as follows
1. Nastic movement is not a growth movement
2. Organisms do not respond to diffuse stimuli in nastic movement
3. In nastic movement, responding to stimuli is very fast
4. Growth in Nastic movement is reversible
5. Nastic movement can be due to changes in cell turgor
6. Nastic movement is non-directional. It is neither positive nor negative response
ENVIRONMENTAL FACTORS THAT EVOKE RESPONSE
There are so many environmental factors that evokes response in living organisms. They are but limited to the following,
iv. Temperature and
The factors effects plants and animals in so many ways. Worthy of note is that equal exposure of plant (CELL) to light diffuses their hormones equally and this makes the growth of plants upward and upright.
Therefore placing a plant in a horizontal position causes an unequal diffusion of hormones. This will make the shoot negatively geotropic by growing upwards. So if a p0lant is starved of adequate light, it tends to respond to any source of light available. The shoot will then respond positively to the source of light while the root will respond negatively.
Invariably the smaller plants in an attempt to get light from the top, automatically grows taller. And so this type of Growth response is called AETIOLATION
ROLES OF AUXINS IN GROWTH MOVEMENT
Auxin is the best known amongst plant hormones. They control tropism by stimulating growth in roots and shoots.
Auxins are produce by the cells in the shoots from where they diffuse to the growing regions. For example, Auxins influence phototropic movements in plants in the flowing ways
i. Auxins are produces at the tip of the shoot.
ii. Auxins diffuse or migrate to growing areas of the plants
iii. The shoot of plants will definitely grow straight as long as there is equal concentration of light and Auxins in all sides
iv. Unilateral illumination of the shoot causes the Auxin to the sides of the shoot moving away from light
v. The increase in the number of Auxin in a particular area makes growth faster
vi. This eventually causes a curvature or bending towards the source of the light thereby resulting in positive Phototropism
HOW LIGHT BRINGS ABOUT TROPIC MOVEMENT IN ROOT AND STEM OF A FLOWERING PLANT
SHOOT OR STEM RESPONSE
1. When unilateral light falls on the stem, the Auxin which is also known as the growth hormone is displaced from the lighted to the dark side.
2. The increase in Auxin concentration on the dark side increases growth on that side, causing the stem to bend toward light known as positive phototropism
I. The Auxin is displaced from the lighted side to the dark side
II. The increase in Auxin concentration in the root retards growth in the dark side, so causing the root to bend away from the light which is known as negative phototropism
MOVEMENT OF THE CELL TYPE OF RESPONSE:
What is movement in living organism?
Do living things actually move from place to place?
So here I will be writing in details of the various way that living organisms including single cell organisms move from place to place in search of food or responding to internal or external stimuli
So the question now is what is movement?
Movement is the ability of living organisms to move from one place to another. Reasons for movement of cell or living organisms are so many but I will like to write on a few of the following.
i. Searching for food
ii. Escape from danger
iii. Positive and negative response to stimuli
iv. For reproduction sake
All organisms that can move from place to place are equipped with various organelles or Organs and other mechanism for movement
CYCLOSIS TYPE OF RESPONSE:
WHAT IS THE MEANING OF CYCLOSIS?
So what is Cyclosis? Cyclosis is the circulation of protoplasm in cells.
Cyclosis occurs in protozoa organisms like Amoeba, and it is generally known as amoeboid movement.
Amoeboid movement is aided by a mechanism called cytoplasmic streaming. It involves the principle of gel-sol conversion of cytoplasm i.e. the varying of the viscosity of cytoplasm and the accompanying fluid pressure at different points within the cell membrane
Movement in amoeba is accompanied by a continuous streaming of the cytoplasm in a forward direction.
This movement is accompanied by the locomotion of the whole cell. In the forward direction, the central plasma sol is converted to plasma gel which remain attached to the inner wall of the plasma membrane but at another point the gel is reconverted in to a sol thereby creating what is called pseudopodium in front and the driving force from behind
TYPES OF ORGANELLES FOR MOVEMENT
There are various types of organelles or organs used by cellular organisms for movement. Organelles which causes movement affecting the whole cells and leading to cellular locomotion in organisms like paramecium, Chlamydomonas and Euglena are flagella and cilia
What is a flagella?
Flagella are long whip-like projections on the cell surface. They are usually one or two on a cell.
Organisms that moves with the aid of a flagella or possess flagella for movement are as follows
What is reproduction?
How reproduction does takes place?
Here you will see the importance of reproduction as concerns living things
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