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TRANSPORT IN LIVING THINGS - Coggle Diagram
TRANSPORT IN LIVING THINGS
THE NEEDS FOR TRANSPORTING SUBSTANCES IN HUMANS AND PLANTS
Unicellular organisms such as bacteria and amoeba do not require a transport system because they are made up of one cell only.
They can obtain useful materials and remove waste products quickly
through simple diffusion because they are in direct contact with the surrounding environment.
Humans and plants are multicellular organisms that are made up of millions of cells.
Many of their cells do not have direct contact with the surrounding environment,
or remove waste substances fast enough through simple diffusion.
so they may not be able to obtain useful substances
Hence, multicellular organisms require an efficient transport system to distribute useful substances e.g. oxygen and dissolved nutrients to millions of cells in the body quickly.
It also ensures a fast and efficient removal of waste substances from the cells to outside of the body.
TRANSPORT IN HUMANS
The transport system in humans is called the circulatory system.
The three main components in the circulatory system are the heart, blood vessels and blood.
When blood flows in one complete circulation in the body, it passes through the heart twice.
Hence, the human circulatory system is also called the double circulation.
The double circulation consists of:
Pulmonary circulation: Blood flowing between the heart and the lungs
Systematic circulation: Blood flowing between the heart and the rest of the body
THE HEART
The human heart is a funnel-shaped, hollow and a powerful muscular organ.
It is responsible to pump blood to all parts of the body.
The structures of the heart:
There are valves present in the heart. They ensure that blood flows in one direction only in the heart.
BLOOD VESSELS
There are three types of blood vessels—arteries, veins and blood capillaries.
Arteries ➤ Blood vessels that carry blood away from the heart
Veins ➤ Blood vessels that carry blood towards the heart
Arteries and veins are responsible for transporting blood in the human body only.
There is no exchange of substances in these blood vessels.
Veins also have valves which ensure blood flows in one direction.
This allows blood to return to the heart from all parts of the body.
Capillaries are very thin and fragile. They are only one-cell thick.
They allow the exchange of substances, such as oxygen, carbon dioxide, nutrients and waste substances, between blood and body cells.
CHARACTERISTICS OF DIFFERENT TYPES OF BLOOD VESSELS
CIRCULATION OF BLOOD IN VARIOUS BLOOD VESSELS
The circulation of blood
pulmonary artery → lungs → pulmonary vein → left atrium → left ventricle → arteries → capillaries (rest of the body) → veins → right atrium → right ventricle
BLOOD
The components of blood and their functions:
Blood is an important component in the circulatory system.
Red blood
They contain haemoglobin to help them transport oxygen more efficiently.
It also carries a small amount of carbon dioxide for removal.
They are responsible for carrying oxygen from the lungs to various parts of the body.
Platelets
They prevent blood loss from damaged blood vessels by forming clots.
Blood plasma
It contains 90% water.
It transports important substances in blood such as:
dissolved nutrients
waste substances
heat
waste substances
hormones
carbon dioxide
It is the liquid part of blood.
White blood cells
They are part of the human immune system.
They help fight against diseases by destroying bacteria.
FREQUENTLY ASKED QUESTIONS (FAQS) ABOUT THE CIRCULATORY SYSTEM
Why is the muscular wall in the left ventricle thicker than that of in the right ventricle?
The left ventricle needs to pump blood to the rest of the body
so it must exert a higher pressure to ensure blood can flow to greater distances.
The right ventricle pumps blood to the lungs which is a short distance
so it only needs to pump blood at a lower pressure.
Why do veins have valves?
The pressure of blood in the veins is very low, so
the valves help blood to move upwards against the gravity to reach the heart from the lower part of the bodies.
Why do arteries have a thicker wall than veins?
Blood flowing in the arteries is at a higher pressure because it needs to flow to the rest of the bodies.
Hence, a thicker wall is needed to withstand the high pressure of the blood.
TRANSPORT IN PLANTS
In a flowering plant, xylem and phloem involve in transporting substances.
Xylem, phloem and cambium are grouped together in vascular bundles in stems.
The cambium produces new xylem and phloem tissues when the plant grows.
Xylem tissues are made up of dead cells and have thick cellulose wall with lignin.It is a hollow vessel for water to flow in it effectively. The functions of xylem:
Provides strength and support to the plant
Transports water and mineral salts from the roots to the stems and leaves
Phloem tissues consist of living cells. They involve in transporting food only.
ARRANGEMENT OF XYLEM AND PHLOEM IN ROOTS, STEMS AND LEAVES
Study the diagram below.
Only part X is stained red when it is placed in a beaker containing red dye for a period of time but not in part Y.
Explain this observation.
Part X is xylem tissue which transports water in plants. As red dye dissolves in water, it is transported together with water.
Part Y is phloem tissue, it only transports food in the plant, so it is not stained red since it does not transport water.
ABSORPTION OF WATER
Roots are one of the organs in plants that are responsible for absorbing water and dissolved mineral salts.
The roots have many elongated structures called root hairs.
These root hairs increase the surface area so that water and mineral salts can be absorbed into the plant at a faster speed.
Water enters the root hair cells by the process of osmosis.
The structure of a root hair cell:
HOW WATER ENTERS A PLANT FROM SOIL TO REACH THE LEAVES OF THE PLANT
root hair cell to root cell A
When water enters the root hair cell, it increases its water concentration and becomes higher than root cell A.
Hence, water moves from root cell A to root cell B by osmosis.
from root cell A to root cell B
When water moves into root cell A, it increases its water concentration inside the cell and becomes higher than its neighbouring root cell B.
Hence, water moves from root cell A to root cell B by osmosis.
from root cell B to xylem vessel
When water moves into root cell B
it increases its water concentration inside the cell and becomes higher than in the xylem vessel.
Hence, water moves from root cell B to the xylem vessel by osmosis.
from soil to root hair cell
When water concentration in soil is higher than inside the root hair cells
water molecules enter the root hair cell by osmosis.
from xylem vessel to leaves
In the leaves, transpiration takes place.
Transpiration is the evaporation of water from the leaves.
Transpiration in the leaves creates a transpiration pull to move water upwards along the xylem vessel from the roots to the leaves.
ABSORPTION OF MINERAL SALTS
When soil has a high concentration of dissolved mineral salts than inside the root hair cells
the mineral salts will enter the root hair cells by diffusion.
No energy is required.
However, during the depletion of dissolved mineral salts in soil
the root hair cells will use active transport to move the dissolved mineral salts from a region of low concentration in soil to the region of high concentration inside the cell.
Energy is required in this process.
TRANSPORT OF FOOD
The phloem tissue will transport the food made in the leaves to all parts of the plant.
In the presence of sunlight, the leaves in a plant carry out photosynthesis to make food.
