Movement in Plants and Animals.

by JamminInJamica (student)

MOVEMENT IN PLANTS AND ANIMALS

Movement is a characteristic of all living organism. It is a reaction to the external/ environmental stimuli and it may involve part of the organism or the entire organism, as n most animals. The direction of the stimulus determines the direction of the response. Locomotion is the movement of the entire organism from one place to another.

Part movement in plants is as a result of growth as a response to various stimuli. For example, plants will grow towards light and their root will grow towards water. Growth responses are usually slow and are not reversible.

Movements in animals, is usually faster than growth movement in plants. Like growth movement, they take place in response to a stimulus, but unlike growth movement, they are reversible. The organism, or its part, can return to its original position when the stimulus is removed.

Movement is important for the survival of all organisms. In animals, locomotion is important for the following reasons:

Finding food

Animals, unlike plants, cannot make their own food and so they have to go in search of food. For example, animals move towards a dead insect; bees fly towards flower to obtain nectar; dogs will chase and kill their prey

Finding a mate

Female birds, attracted by the singing of male birds, will go in search of a suitable male; male dogs will respond and find female dogs when they are in heat.

Escaping from predators

Animals which are preyed on will move to prevent being eaten e.g. house flies fly away to avoid being eaten by lizards; an earth worm moves underground to avoid birds.

Finding a more favourable environment

Earth worms are soft bodied creatures which respire through their body surface. The body surface must be kept moist for gases to diffuse across the surface. ...

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Finding a mate

Female birds, attracted by the singing of male birds, will go in search of a suitable male; male dogs will respond and find female dogs when they are in heat.

Escaping from predators

Animals which are preyed on will move to prevent being eaten e.g. house flies fly away to avoid being eaten by lizards; an earth worm moves underground to avoid birds.

Finding a more favourable environment

Earth worms are soft bodied creatures which respire through their body surface. The body surface must be kept moist for gases to diffuse across the surface. They move away from light. This ensures that they stay underground where it is damp and dark and so avoid desiccation. Some birds migrate to warm countries to avoid the harsh winter weather.

These responses ensure that animals survive long enough to produce new offspring.

EXTERNAL FACTORS AND PLANT MOVEMENT

Growing plants respond to stimulus such as light and gravity. Movement towards a stimulus is a positive response; movement away from a stimulus is a negative response. If the stimulus is applied from one direction the response is usually in one definite direction; away from or toward the direction of the stimulus.

The stimulus is received by the tip of the shoot or root and growth response takes place just behind the tip. For example, plant shoots will grow towards a light source. Plant hormones, called auxins, are made at the tip of roots and shoots. They diffuse downwards and away from the light source. The cells in the region where they accumulate grow faster than other cells causing bending in that region.

Different parts of the same plant may respond differently to the same stimulus. Shoots respond positively to light; roots respond negatively. This is important because light is essential for photosynthesis, the process by which green plants manufacture food. Light is also essential for chlorophyll formation. Roots respond positively to the downward force of gravity; shoots respond negatively. This response ensures that the roots become firmly anchored in the soil and is able to obtain water and nutrients.

STRUCTURE AND FUNCTION OF THE SKELETON IN MAN

The skeleton in Man is a rigid structure formed from bone and cartilage. As is other vertebrates it is located within the body and is termed an endoskeleton (Arthropods have an exoskeleton which covers the body.)

Bones is very strong and rigid and consists of living cells surrounded by hard mineral substances; mainly calcium and some carbonates and phosphates. These mineral salts give bones their strength and shape. Spongy bones consist of a meshwork which make it very light. Dense bone is more solid and heavy.

The general plan of the mammalian skeleton

The skeleton of man is divided into two main parts:

The axial skeleton which consist of the skull, the vertebral column (backbone or spine), and the ribcage.
The appendicular skeleton made up of the pectoral girdles, the pelvic girdles and bones of the arm and leg.

The Axial Skeleton

The skeleton is made up of several bones securely held together. The vertebral column consists of several bones, called vertebrae, which together form a strong flexible rod running along the length of the body. There are four distinct region; cervical or neck; thoracic or chest; lumbar of small of back and sacral or lower back.

The Appendicular Skeleton

The pectoral girdle consists of two clavicles (collar bone) and two scapulas (shoulder blades). The pelvic girdle consists of two hip bones; each made up of three bones tightly joined together to form a bowl.

The functions of a skeleton

The skeleton performs several functions. These include:

Protection

Some soft tissues are protected by the skeleton. The skull protects the brain, inner and middle ears, nasal organs and the eyes. The heart and lungs are protected by the rib cage and the spinal cord is protected by the vertebral column. The reproductive organs in females are protected by the pelvic girdle.

Support

The skeleton forms a rigid framework which maintains body shape. The limb supports the body above the ground.

Movement and locomotion

The bones provide points of attachment fro muscles and the bones act as levers and joints as pivots; when muscles contract, movement occurs.

Blood formation

Blood is produced in the red bone marrow. In children, red bone marrow is found in almost all bones; in adults, marrow in the shaft of long bones become inactive; blood formation is restricted to areas like the skull, ribs, sternum (breast bone) and vertebrae.