Respiration

What are the Characteristics of Living Things

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What are the Characteristics of Living Things

Characteristics of living things
The characteristics of living things are described below.

Structural Organization
Living things have a definite structural organization. Their bodies are made of cells, which are the building blocks of the body.

What are the Characteristics of Living Things 1
Structural organization in living things
  • A cell is the smallest living structure that is able to function independently.
  • A group of similar cells that perform a particular function form a tissue.
  • A group of tissues performing a particular function in the body form an organ.
  • A group of organs interacting with one another to perform a particular life process like digestion, respiration, etc., form an organ system.

There are organisms made of just one cell. An organism whose body consists of a single cell is called a unicellular organism, e.g., Amoeba and Paramoecium. In a unicellular organism, all life processes are carried out by the single cell.

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Amoeba
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Paramoecium

An organism whose body consists of several cells is called a multi cellular organism, e.g., human beings and a rose plant.

Movement and Response to Stimuli
Most living things are capable of moving on their own. Animals move from place to place in search of food and water and to escape from danger.

Plants do not move on their own. However, they exhibit movement of their certain parts, like leaves and roots, in response to changes in their immediate environment.

A change in the immediate environment of an organism, which produces a change in the activities of the organism, is called a stimulus (plural: stimuli). An organism’s reaction to a stimulus is called a response.
Leaves of touch-me-not curl up when touched. Here, touch is the stimulus and curling up of leaves is the response.
Shoot of a plant grows towards the light and the root grows towards gravity. Here, light and gravity are the stimuli and plant growth is the response.

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plant responds to light and gravity

Growth
Living things grow. For example, a child grows into an adult and a seedling grows into a plant. Growth in living things is irreversible. For example, we cannot get the seedling back from the plant.

Excretion
Living things remove wastes from their body by the process of excretion.
Most animals excrete solid wastes in the form of faces, liquid wastes in the form of urine, and gaseous wastes in the form of carbon dioxide.
Gum, resins, latex, are some wastes given out by plants.

Respiration
The process by which living things utilize oxygen to release energy stored in the food they eat is called respiration. Plants and animals respire all the time.
Breathing is a part of respiration. By breathing, we inhale air which contains oxygen. It is through respiration that this oxygen is used by the body to obtain energy from food. Plants also respire to obtain energy from the food they make by photosynthesis. Thus, respiration is a vital process for all living organisms.

Reproduction
Living things have the ability to reproduce more of their kind through reproduction. Different organisms have different means of reproduction. Plants reproduce mostly through seeds. Animals reproduce by either laying eggs or giving birth to young ones.

Feeding
All living things need food. Green plants manufacture their own food by photosynthesis. Hence, they are called autotrophs {auto, self; trophe, food).
Animals cannot manufacture their own food. Hence, they are called heterotrophs {hetero, different; trophe, food). They depend on plants and other animals for food.

Life Span and Death
All living things follow a cycle of growth and development in which an organism takes birth, grows into an adult, grows old, and dies. This is known as the life cycle of the organism.

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Life cycle of a hen

Differences between living and non living things:

Living thingsNon-living things
1. Living things are made of cells.1. Non-living things are not made of cells.
2. They excrete and get rid of wastes.2. They do not produce wastes.
3. They reproduce new offspring.3. They do not reproduce.
4. They need food and air to stay alive.4. They do not need food or air to stay alive.
5. Living things follow a cycle of growth and they finally die.

5. Non-living things do not grow or die.

Mechanism Of Respiratory System

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Mechanism Of Respiratory System

Respiratory centre is in Medulla Oblongeta.
Mechanism of breathing involves Two Phases.
(A) Inspiration
(B) Expiration
Inspiration:
Intercostal and phrenic muscles of diaphragm contract to increase thoracic cavity, therefore outside rushes inside.
Expiration:
Intercostal & phrenic relex muscles.
Due to decrease of thoracic cavity air pressure within lungs increase, the greater pressure within lungs force ful air from lungs to outside of body.
Gaseous Exchange:
Gaseous exchange occur in Alveoli following pressure gradient O2 from high pressure in alveoli diffuse into blood & CO2 from blood in alveoli.
Gaseous Transport:
O2 is carried by haemoglobin (in RBC). 100 ml of blood can carry ~20 ml of O2 max, CO2 is transported in form of bicarbonates in plasma.

Mammalian Respiratory System

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Mammalian Respiratory System

mammalian-respiratory-system
The mammalian respiratory system consists of nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles and alveoli.
Nostril:
It is also called external nares.
Nasal Chamber:
Nasal septum divides nasal cavity into two nasal chamber by the nasal septum.
Internal nares:
There are posterior opening of nasal chambers that leads into pharynx.
Pharynx:
The pharynx provides passage to both air and food.
Laryngopharynx:
It is the lower part of pharynx and has a slit like aperature called glottis, which can be closed by a leaf like bilobed cartilage epiglottis, during swallowing of food bolus.
Larynx:
It is also called voice box or adam’s apple or pomas adami.
Vocal cord:
In larynx, 2 pairs of vocal cord is found outer pair is false vocal cord whereas, inner pair is true vocal cord when air is forced through the larynx it cause vibration of true vocal cords and sound is produced.
Trachea (Wind pipe):
It is long, tubular structure which runs downward through the neck in front of oesophagus. It is supported by cartilage to prevent collapse.
Primary bronchi:
These are one pair of small thin walled tubular structure formed by the division of trachea. It further divides and end at alveoli.
Lungs:
lungs are present in thoracic cavity on either side of heart. covered by pleural membrane.

Respiration In Plants

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Respiration In Plants 

By young roots:
Air occurs in soil interspaces. Root hairs as well as epiblema cells of the young roots are in contact with them. They are also permeable to metabolic gases. Oxygen of the soil air diffuses through root hair-epiblema cells and reaches all internal cells of the young root. Carbon dioxide produced by root cells diffuses in the opposite direction.
respiration-in-plants
By Leaves:
Leaves and Young Stems. Leaves and young stems are ideally suited to quick exchange of gases. The organs have a covering of nearly impermeable epidermis for reducing loss of water. The epidermis of leaves bears a number of aerating pores called stomata (singular stoma or stomata, Gk. stoma-mouth). Each aerating or stomatal pore is bordered a pair of guard cells. In most of the plants, the guard cells are kidney or bean shaped with inner walls being thicker and less elastic than the outer walls.
When the stomata are open, gases diffuse into and out of the leaf as per their concentration gradient. A gas which has come from outside first reaches substomatal chambers. From here, it diffuses to all the intercellular air spaces present in between the mesophyll cells. If the stomata are open during night, oxygen from outside will diffuse into the leaves and young stems while carbon dioxide will diffuse out. It is due to respiratory gas exchange.