CHAPTER 5 TRANSPORTATION IN ANIMALS AND PLANTS
TRANSPORTATION IN ANIMALS
The function of the circulatory system is to transport the substances to and from the various organs of the body.
Blood is the medium through which all substances are transported.
The fluid part of the blood is known as ‘plasma’. The cells which contain the red pigment are called ‘red blood cells’ and the red pigment itself is called ’haemoglobin’ which facilitates the transport of oxygen. The blood also contains ‘white blood cells’ which protect the body against diseases. Blood also has ‘platelets’ which are responsible for clotting of blood in case of injuries.
Arteries carry oxygen- rich blood from the heart to the other parts of the body.
Veins carry carbon dioxide- rich blood from the body to the heart for purification.
Heart is the most vital organ of the body. It pumps blood to various parts of the body. The heart has four chambers. The upper two chambers are the atrium and the two lower chambers are the ventricles
The process of removal of waste from the body is called excretion. All the parts involved in this process form the excretory system. The liquid wastes are produced when the kidneys filter out the blood and store the waste in the urinary bladder. This waste is then passed out in the form of urine.
TRANSPORTATION IN PLANTS
Plants absorb water through the roots. There is a vascular tissue called xylem through which nutrients and water are transported to the entire plant. The vascular tissue that transports food to the entire plant is called phloem.
Water is absorbed by the plant because of transpiration. Transpiration is when the leaves of the plant lose water through evaporation. Due to this loss of water a suction pull is created and the water is pulled up through the roots.
CHAPTER 4 RESPIRATION IN ORGANISMS
NEED FOR RESPIRATION
A cell is the smallest functional unit of an organism. To perform the bodily functions, cells need energy. This energy comes from respiration.
The food that we eat stores energy in it. The oxygen that we breathe is transported to each cell of the body. Using this oxygen, cells break down food and release energy. This process is called cellular respiration.
When food is broken down in the presence of air, it is called aerobic respiration
When food is broken down without the presence of air, it is called anaerobic respiration. When we do some heavy exercise, the supply of oxygen to the muscles reduces and anaerobic respiration occurs.
Breathing is the process of taking in oxygen and giving out carbon dioxide.
We take in oxygen though our nose which reaches the lungs through the wind pipe. This process is called inhalation. We then give out air consisting mostly of carbon dioxide and this is called exhalation. The number of times we breathe in a minute is called breathing rate. Inhaling and exhaling once is called one breath.
The breathing rate may change according to the type of activity a person is doing. While relaxing, the breathing rate is less whereas while any brisk physical activity such as running or exercising increases the breathing rate.
When we inhale, the air passes through the nostrils, moves down the windpipe, and reaches our lungs. The lungs are in the chest cavity which is surrounded by ribs on the sides. When we inhale, the ribs move up and outwards, the diaphragm moves down which increases the space in the chest cavity and the lungs get filled with air.
When we exhale, the ribs move down and inwards, the diaphragm moves up and the chest cavity gets reduced in size which pushes out the air.
Breathing in other animals:
Most insects have small openings on the sides of their body called spiracles. They have a network of tubes called trachea for gas exchange.
Animals like earthworms breathe through their skin.
Animals living under water, such as fishes, have small projections of the skin called gills which help them in absorbing oxygen dissolved in water.
RESPIRATION IN PLANTS
While plants perform photosynthesis during the day and give out oxygen, during the night they perform respiration just as any other living being. They take in air, absorb oxygen and release carbon dioxide.
CHAPTER 3 WEATHER, CLIMATE AND ADAPTATION OF ANIMALS TO CLIMATE
Weather of a place is the day-to-day atmospheric condition in terms of temperature, rainfall, humidity, rainfall, wind speed, etc.
The average weather pattern recorded over a long time is called the climate of the place.
CLIMATE AND ADAPTATION
Animals have to adapt to survive in the climatic conditions they live in. Animals living in extremely cold climatic conditions have features like thick fur coat to protect them from cold whereas animals living in the hot conditions develop resistance to heat and scarcity of water.
Different climatic regions:
(i) The Polar Regions
(ii) The tropical rainforests
CHAPTER 2 NUTRITION IN ANIMALS
HUMAN DIGESTIVE SYSTEM
(i) The mouth and the buccal cavity
The process of taking food through the mouth is called ingestion.
We have teeth that help us in chewing our food and breaking it down for swallowing.
Our tongue helps in mixing the saliva with the food. The taste buds are also located on the tongue.
(ii) The food pipe
After the food is properly chewed and mixed, it is swallowed which transfers it to the food pipe. The food pipe is also called the ‘oesophagus’. It connects the mouth to the stomach. The alimentary canal is a part of the food pipe which, due to the movements of its walls, pushes the food down to the stomach.
(iii) The stomach
The stomach is a thick walled bag shaped like a flattened U. the inner lining of the stomach secretes mucous, hydrochloric acid and digestive juices. The stomach opens into the small intestine.
(iv) The small intestine
The small intestine is about 7.5 metres long and is highly coiled. Both the liver and the pancreas secrete liquids into the small intestine. Liver is a reddish brown gland which is situated on the upper part of the right side abdomen. It is the largest gland in the body and secretes bile juice which is stored in the gall bladder. The pancreas is a gland situated right below the liver. The juices secreted by pancreas act on carbohydrates and proteins to convert them into simpler forms. The food is partially digested now and it reaches the lower small intestine.
The lower intestinal walls absorb the digested food through the blood vessels in them. The inner wall of the small intestine has finger-like outgrowths called villi which increase the surface area for absorption. The absorbed nutrients are transported to different organs of the body where they are further transformed into complex substances. This process is called assimilation.
(v) The large intestine
The large intestine is wider but shorter than the small intestine. It absorbs some salts and water from the undigested food. The remaining undigested food is excreted out of the body as faeces through the anus.
DIGESTION IN GRASS EATING ANIMALS
The grass eating animals like cows and buffaloes quickly swallow the grass and store it in a separate part of the stomach called rumen where it gets partially digested. This partially digested food is called cud. It later returns to the mouth in small lumps. The animals then chew it. Such animals are called ruminants and the process is called rumination.
DIGESTION IN MICROSCOPIC ANIMALS
A microscopic animal, an amoeba, for example, pushes out finger like projections called pseudopodia for movement and capturing food. It engulfs the food particle which gets trapped in a food vacuole and digestive juices are released in order to digest it. The undigested residue of the food is expelled.
CHAPTER 1 NUTRITION IN PLANTS
Food is a basic necessity for all living things. Plants make their own food by photosynthesis but animals cannot. Some animals directly eat plants and some eat other animals that eat plants which means that directly or indirectly, we all depend on plants for food.
MODE OF NUTRITION IN PLANTS
Plants come under the category of ‘Autotrophs’. Autotroph is made up of ‘Auto’ which means ‘self’ and ‘trophos’ which means ‘nourishment’. Animals that obtain their food from plants are called ‘Heterotrophs’. Heterotroph is made up ‘Heteros’ which means ‘other’ and ‘trophos’ which means ‘nourishment’.
Photosynthesis occurs in the leaves of the plant. The raw materials required for photosynthesis, therefore, are transported to the leaves.
The roots absorb water and minerals from the soil and transport it to the leaves through the vessels which run throughout the roots, stem, branches and the leaves.
Carbon dioxide is taken in from the atmosphere. On the surface of the leaves, there are tiny pores (called ‘stomata’) surrounded by guard cells.
The leaves also contain a green pigment called ‘chlorophyll’ which helps absorb the energy of the sunlight.
The chemical reaction of photosynthesis can be represented as:
Carbon Dioxide + Water (In Presence if Sunlight & Chlorophyll) → Carbohydrate + Oxygen
The chlorophyll containing cells use the sunlight, water and carbon dioxide to produce carbohydrates and give out oxygen. The carbohydrates get stored as starch.
Plants which do not have chlorophyll depend on other plants for their food.
There are various insect eating plants such as the Pitcher plant. Such plants are called insectivorous plants. The leaf is modified into a pitcher which has hair directed downwards. The insect gets trapped in the hair and is then digested by the digestive juice released in the pitcher.
The organisms which obtain their nutrition from dead and decaying matter are called saprotrophs. For e.g. Fungus
In a symbiotic relationship, organisms provide nutrition to each other. When crops require nitrogen to make proteins, they cannot absorb nitrogen from the air. A bacterium called Rhizobium can covert the atmospheric nitrogen into soluble form. Plants provide food and shelter to the bacteria and the bacteria in return convert nitrogen into a soluble form for the plants. These plants are generally the leguminous plants.
CHAPTER 7 WASTE WATER
The waste water released by homes, industries, hospitals, offices, etc. is called sewage. Sewage is basically liquid waste. The impurities that sewage contains are called contaminants.
Sewage treatment is the process of removing pollutants or contaminants from the waste water.
WASTEWATER TREATMENT PLANT (WWTP)
Measures to reduce sewage and diseases
CHAPTER 6 FORESTS
Forest is an entire system of plants, animals and micro-organisms. They are a home to a number of animals and plant species. The uppermost layer i.e. the canopy is formed by the trees. The shrubs form the middle layer. The lowest layer of vegetation is formed by herbs
Forests influence the climate, water cycle and air quality.
Forests prevent soil erosion as the roots hold the soil firmly. Decomposers are micro-organisms that decompose the dead plants and animals and produce humus, which makes the soil more fertile.
Forests improve air quality as plants give out oxygen during photosynthesis. They absorb carbon dioxide and therefore reduce air pollution. They also reduce noise pollution.
To ensure that the balance of nature remains intact forests need to be conserved. Deforestation has to be reduced. Deforestation is the cutting of trees from the forest. Afforestation has to be promoted.
CHAPTER 5 WATER
About 71% of earth’s surface is covered in water but most of it cannot be consumed as it is in the oceans and seas. The water in the oceans and seas is too salty to be consumed. Only the freshwater available in rivers and lakes is fit for consumption. Freshwater is about 0.006% of the total water and even this water is being quickly used up.
FORMS OF WATER
Water exists in all three forms:
(i) Solid: As snow and ice in the glaciers and ice caps
(ii) Liquid: In oceans, seas, rivers, lakes, groundwater
(iii) Gas: As water vapour in the atmosphere
The continuous cycle of water among its three forms is called water cycle
Water seeps into the ground through the process of ‘infiltration’ and gets stored as ground water. The upper limit of ground water is called the water table.
Depletion of water table
Ground water is drawn and used for everyday purposes. Excessive usage of ground water leads to depletion of water table. The major reasons for depletion of water table are:
DISTRIBUTION OF WATER
The distribution of water is uneven due to climatic conditions and uneven rainfall,
We have limited amount of water available and therefore it must be managed carefully. It is important to follow practices such as rain water harvesting, drip irrigation, etc. so as to save water.
CHAPTER 4 SOIL
A soil profile is a vertical section through which different sections of the soil can be seen. The different layers are also known as Horizons.
Soil contains sand and clay. The proportion of particles determine the kind of soil.
PROPERTIES OF SOIL
1. Percolation rate of water
Percolation rate is the gradual movement of water through the soil.
Percolation rate= Amount of water(mL) / Percolation time(min)
2. Moisture in soil
It is the amount of water in the soil.
3. Absorption of water
The capacity to absorb water by the soil is called absorption capacity. Different soils have absorption capacity.
SOIL & CROPS
Removal of top soil by wind, water or ice is called soil erosion. This degrades the soil quality.
CHAPTER 3 PHYSICAL AND CHEMICAL CHANGES
Changes occurring around us can be broadly divided into physical and chemical changes.
When a substance experiences a change in its physical properties like shape, size, colour or state, it is called physical change. Physical change does not form any new substance.
When a substance undergoes a change in their chemical properties, it is called a chemical change. A chemical change is also called a chemical reaction and leads to the formation of new substances.
E.g. (i) Rusting of iron
The process of rusting is as follows:
Iron + Water + Oxygen → Rust
Fe + H2O + O2 → Fe2O3
When iron is left out in the open, a brownish film is formed over it. The brown film is called rust and this process is called rusting of iron.
To prevent rusting, iron is coated with a layer of zinc. This process is called galvanization.
A crystal of a substance is its pure solid form. Obtaining a substance in its pure form from its solution is called crystallization.
Depending on the changes, they may be classified into reversible or irreversible.