Important Topics of Biology to Be Covered

Types of Environment

If we talk about the types of environment, there are many. It is not easy to make a proper classification of the environment, looking at the diversity of the world in which we live. But there two commonly known and accepted types of environment – natural or geographical environment, and manmade environment. Before discussing them, let’s have a look at what is environment –

In simple words, the environment is our surroundings in which we live – it includes both the biotic and abiotic factors around us. We live in an environment, which may be a natural, social, or a built environment. These are the surrounding conditions in which humans, plants, and animals live.

And every individual existing in the environment has an impact on it, and the environment also influences individual behavior. Thus, it can be perfectly said that individuals and the environment are related and are complementary to each other.

The existence of the environment is very important because not only human life, but any living life just cannot survive without it. It provides natural beauty, maintains the balance of life, supports the food chain, and supports living lives and their various activities.

Types of environment

The classification of the environment broadly divides it into two categories – Geographical and Manmade environment.

Geographical environment

Geographical environment is also called the natural environment because it consists of all the components provided to us by nature. It is not dependent upon humans for its existence, but it does get affected by human activities.

The natural environment definition tells us that it includes earth surface, rivers, mountains, deserts, land, water, oceans, volcanoes, and everything. These are some natural environment examples.

Man-made environment

Man cannot directly live in the geographical environment, so he creates some of his environmental conditions to adjust to it. This is a manmade or human made environment, a human creation.

A manmade environment is also called a social environment. It has two types –

The Inner environment

The inner environment depends upon the existence of the society. It consists of customs, traditions, regulations present in every human social group. It is the same concept to which we also call non-material culture or heritage.

The inner environment has a profound impact on human lives. It is important to cherish human lives, and thus people consider it to be important to carry forward for their next generations.

The Outer environment

This consists of the material or physical aspect of the manmade environment. The development of the outer environment depends upon the development and progress of mankind.

It includes city infrastructures, houses, various amenities provided at the social and individual level, transport and communication, and much more. It can be said that the outer environment changes more rapidly than the inner one.

Frequently asked questions

1. What are the main types of environments?

The environment is broadly divided into two categories – Geographical environment and Manmade environment.

2. What is meant by the geographical environment?

Geographical environment is also known as the natural environment, and it consists of all the components of natural components such as air, water, river, mountains, land, deserts, and many more.

3. What does a manmade environment mean?

The manmade environment, as the name suggests, is created by human beings. it includes inner aspects such as customs and traditions, and outer aspects such as physical developments in the society.

4. What is the importance of a geographical environment?

Geographical environment is provided to us by nature, and all these natural resources help in the survival of mankind. But an excessive use and careless attitude towards them will in turn cost us badly, in the form of natural disasters and scarcity of resources.

5. How can I differentiate between geographical and manmade environments?

A manmade environment includes every material and non-material concept created by man. It will exist as long as human society exists. But geographical environment includes everything natural, and it does not depend upon human existence for its existence. This is an easy way to differentiate between these two.

6. How does environmental pollution take place?

When different human or natural activities release harmful substances into the environment, which can have an adverse effect on the components of the natural environment, then it is called as environmental pollution.


What is Blood?

What is blood? It’s a fluid that circulates through our body, and is very essential in the survival of the humans. They perform various important functions in our body. A normal person has around five to six liters of blood in his body.

Types of Blood Cells

Blood consists of blood cells, each of whom have their function. The blood cells that circulate in our body are:

Red blood cells (Erythrocytes)

They are rich in iron proteins called hemoglobin that gives them their red color. They supply oxygen to all the tissues and organs in our body.

White blood cells (Leucocytes)

These blood cells don’t have any color, support the immune system, and form the defense mechanism of the body.

Types of White Blood Cells

White blood cells are divided into 5 categories, but they are mainly divided into 2 types based on the presence or absence of the granules in them. These two types are:

  • Granulocytes
  • Agranulocytes


Granulocytes have granules in their cytoplasm. The granulated blood cells are divided into the following categories:


These are found in our immune system and they fight the infections.


Having large granules in their cytoplasm, basophils play a role in asthma, and they result in inflammation as well as bronchoconstriction.


A60 to 70% of the white blood cells are neutrophils, and they are the first respondent cells to the foreign bacteria or viruses.


These types of leukocytes don’t have granules in their cytoplasm. They are further subdivided into:


Called as the garbage truck of our immune system, the bean-shaped monocytes clean up the dead cells by migrating into the tissues, and protect the tissues from pathogens born in the blood.


Lymphocytes or natural killer cells play a crucial role in the production of antibodies.

Platelets (Thrombocytes)

Platelets make their contribution when there’s bleeding or hemorrhage. They help the clotting process when a cut or wound occurs.

Components of Blood

The composition of blood contains many components. When a centrifugal machine spins a blood sample, it is separated into plasma, buffy coat, and erythrocytes.


Plasma fluid forms more than 50% of the composition of blood, and that’s why it could be the reason behind the liquid state of the blood. It is pale yellow and is a mixture of salts, water, enzymes, proteins, and nutrients essential for good health.

Red Blood Cells (RBC)

RBCs produced in the bone marrow mainly do the job of carrying oxygen to the body parts, and it also consists of hemoglobin, a protein essential for a healthy body.

White Blood Cells (WBC)

White blood cells are those warriors that fight the foreign pathogens entering our body.


These are of a shape of a tiny disc, and they control the blood flow to help repair the damaged part of the body, where clotting has formed.

Blood Vessels

The blood flows to various parts of the body through the blood vessels. and there are a few types of blood vessels, and each of them carries out a special function different than the other.

Types of Blood Vessels

There are three types of blood vessels. These are:

  • Arteries
  • Veins
  • Capillaries


Arteries carry oxygen-rich blood and are very strong. The aorta is the biggest artery coming from the heart, which further divides itself into many branches.


Veins are elastic, and they carry oxygen-lacking blood from various body parts to the heart for the purification process. Only umbilical and pulmonary veins carry oxygen-rich blood.


Arteries are further divided into fine capillaries, and they do the function of exchanging substances between tissues and blood.


These are very fine blood vessels present in the bone marrow, liver, and spleen.

Layers of Blood Vessels

There are three layers of blood vessels:

Tunica Intima: This innermost layer of arteries and veins is made up of endothelial cells. It has an inner, middle, and outer layer, and is in direct contact with the blood flow.

Tunica Media: consisting of connective tissue along with polysaccharide substances, this is the thickest layer that controls the caliber of the vessels.

Tunica Adventitia: it also does the function of controlling caliber, and is surrounded by tunica media.

Functions of Blood

There are various functions of blood, which is an essential body fluid for the survival of humans. These functions are:

Fluid Connective Tissue

Blood is not just a fluid tissue, but a fluid-connective tissue spread across the body. It comprises of plasma and other components like blood cells, platelets, etc.

Provides oxygen to the cells

After absorbing oxygen from the lungs, blood transports it to the various parts of the body. It helps in removing the waste CO2 from the body.

Transports Hormone and Nutrients

Nutrients like vitamins, minerals, and proteins are absorbed by blood for transporting them to various body parts. Also, endocrine glands secrete many hormones that are also transported by the blood, to the target organs and tissues.


Blood facilitates homeostasis by helping to maintain the body temperature. This is done by absorbing or releasing the heat.

Blood Clotting at Site of Injury

When an injury occurs, blood helps to create a clotting at the damaged part.

Transport of waste to the Kidney and Liver

The toxic substances and waste are carried to the kidneys for filtration by the blood itself. The liver also removes the toxins present in the blood.

Protection of body against pathogens

The WBCs in the bloody fight against the various pathogens trying to enter the human body. Lack of WBCs can invite many health problems.

Frequently Asked Questions

1. What are the components of blood?

The components of blood are Plasma, RBCs, WBCs, and Platelets.

2. Where are red blood cells formed?

The red blood cells are formed in the soft tissues inside the bone cavities, known as a bone marrow.

3. What is the composition of blood?

Blood is a special body fluid composed of – 55% plasma, and 45% cells and fragments such as RBCs, WBCs, and platelets. Blood also has some antibodies, hormones, and electrolytes.

4. What are the types of blood cells?

The types of blood cells are red blood cells (RBCs) also known as Erythrocytes, and white blood cells (WBCs) known as Leucocytes.

5. Is blood a tissue?

Yes, blood is a tissue that is fluid-connective.

6. What are some important functions of blood?

The important functions of blood include supporting homeostasis, providing oxygen to the cells, transporting hormones, and helping the clotting process after any injury.

Difference between Nucleus and Nucleoid

Before understanding the difference between nucleus and nucleoid, we will first have to understand what is a cell. A cell is the most basic structural and functional biological unit present in living organisms. It can be said that just as non-living things have atoms as their basic units, living organisms have cells.

Cells also have their organelles such as the nucleus, mitochondria, Golgi bodies, and cytoplasm. Those cells whose organelles are enclosed in a membrane are called eukaryotic cells. And those cells that do not have membrane-bound organelles are prokaryotic cells.

In the eukaryotic cells, the nucleus performs the function of storing genetic material along with controlling cellular activities. And in the prokaryotic cells, nucleoid does the same, along with providing support to the growth and development of a prokaryotic cell.

Both the nucleus and nucleoid are very important in their respective terms. Both the nucleus and nucleoid have DNA present in them, which is essential for the storage of genetic material.

Nucleus vs. Nucleoid

In order to differentiate between nucleus and nucleoid, what we have to understand their structure. Nucleus and nucleoid are found in eukaryotic and prokaryotic cells respectively, and they are responsible for some important functions.

While understanding is the difference between nucleus and nucleoid, their structure and function must be understood carefully. It is observed that there are many differences as well as similarities found in both of them.

A major difference between nucleus and nucleoid is that the nucleus is enclosed in a membrane.A nucleoid is not enclosed in a membrane like nucleus.
Nucleus is an important cell organelle.Nucleoid is a specific area in prokaryotic cell which has almost same functions like that of the nucleus.
Nucleus has an organised structure against the nucleoid.Nucleoid has an unorganised structure.
Nucleus contains many chromosomes.Nucleoid has only one chromosome in it.
Nucleus in the eukaryotic cells is well-protected with a double-layered membrane.Nucleoid, on the other hand, does not have any protective membrane.
Talking about nucleus vs. nucleoid, nucleus is the largest cell organelle.Another difference between nucleus and nucleoid shows that nucleoid is comparatively small in size.
Nucleus has a spherical shape.Nucleoids are not found in any particular shape.

Though there are many points to differentiate between nucleus and nucleoid, there are some similar features too. To talk about it, the nucleus comprises DNA, RNA, enzymes, histones, some subnuclear bodies, and dissolved ions.

            And most of these components are present in nucleoid too. They also contain DNA, RNA, histones, and some other proteins. After studying all these, let’s have a look at the meaning of nucleus and nucleoid.

Nucleoid meaning

Nucleoid is a particular area in the prokaryotic cell that stores the genetic material. This material is known as a genophore, or prokaryotic chromosome. The genetic material storing DNA is present in the nucleoid. But nucleoids have a different structure and organization.

Nucleus meaning

The nucleus is the largest enclosed organelle in eukaryotic cells responsible for the storage of genetic information. It keeps coordination with other cell organelles to control cellular activities.

The nucleus plays an important role in facilitating the process of transcription and replication. It occupies the largest part of the cell, which is nearly about one-tenth of the cell.

Frequently asked questions:

1. What is meant by the nucleus?

The nucleus is the central organelle present in the eukaryotic cells that stores genetic information. It’s the largest cell organelle in the eukaryotic cells and plays a very important role in the life-cycle of a cell.

2. What is meant by nucleoid?

Nucleoid is a particular part present in the prokaryotic cells, responsible for storing genetic materials. It is a small, unorganized part of a prokaryotic cell that is unorganized, but performs some very important functions.

3. What functions are performed by the nucleus?

The main functions of a nucleus are to store the genetic information, along with controlling cellular activities.

4. What functions are performed by nucleoid?

The nucleoids contain assisting the growth of cells, and storing hereditary information just as the nucleus does in eukaryotic cells.

5. Which organisms have a nucleus and nucleoid?

Organisms with eukaryotic cells have a nucleus, and the organisms with prokaryotic cells that don’t have closed membranes, have nucleoid. 

Significance of Meiosis

In simple terms, meiosis is a process of cell division. During this process, the parent cells get divided into four daughter cells. These four daughter cells include half of the original genetic information that their parent cells contain.

Thus, the daughter cells formed during the meiosis process are called haploid cells. Meiosis also produces gametes. Because of all this, it is necessary to understand the significance of meiosis.

To understand the importance of meiosis, consider its role in the process of sexual reproduction. It is a cell division of a special type. And the process of meiosis is very important in organisms having eukaryotic cells because it will further lead them to sexual reproduction.

The process of meiosis beings with/takes place in diploid cells, and results in the formation of haploid cells. One of the diploid cells is the mother cell, and the other one is from the father.

Features of meiosis

  • The cell division in organisms is of two types – mitosis and meiosis. And meiosis is a cell division process that divides the parent cells two times, leading to the formation of haploid daughter cells.
  • The result of the process of meiosis is a formation of 4 daughter cells. These are formed during each cell division cycle.
  • The shape and size of the daughter cells are identical to that of the mother cell. But the number of chromosomes in the mother cell and daughter cells is not the same, it’s different.
  • The nature of the daughter cell formed during the meiosis process is haploid. It is because the parent cells, during the process, are divided two times each. And 4 daughter cells are formed.
  • During meiosis two cell divisions are done. And the process of recombination as well as segregation also takes place.
  • This process takes place in reproductive organs. And the result of this process is seen as the formation of gametes.
  • Meiosis is divided into two types – Meiosis-I is also known as the process of reductional division. In meiosis-I, the number of chromosomes is reduced to half. And the next type, meiosis-II, is similar to the process of mitotic division.


  1. In order to understand the importance of meiosis, and the significance of meiosis, we have to see its outcomes, and what do they lead to.
  2. Meiosis leads to the formation of sex cells or sex gametes. They are further responsible for the process of sexual reproduction.
  3. The process of meiosis performs the dual functions of activating genetic information and deactivating sporophytic information. The activated genetic information facilitates the development of the sex cells.
  4. We know that the number of chromosomes get doubled after the process of fertilization. So, to balance the number of chromosomes, the process of meiosis reduces them to half.
  5. During meiosis, the maternal and paternal chromosomes are assorted. So, the chromosomes and their traits are reshuffled after the meiosis.
  6. Because of the irregularities in the cell division caused by meiosis, the process of genetic mutation takes place. After that, a natural selection takes place to carry on the beneficial genetic mutations.
  7. The crossing over caused by meiosis leads to the formation of new combinations in terms of traits and variations.
  8. Thus, if one is asked to write the significance of meiosis, one has to keep in mind all the outcomes resulting from the process of meiosis.

Frequently asked questions:

  1. What is meiosis?

Meiosis is a special type of cell division process taking place in diploid cells, that results in the formation of haploid cells.

  • What are the outcomes of a meiosis?

Because of the process of meiosis, four daughter cells are formed that are haploid in nature. This further facilitates the sexual reproduction process.

  • In which organisms does meiosis occur?

The process of meiosis occurs in those organisms that have eukaryotic cells. It is essential for sexual reproduction in eukaryotes.

  • Where does the meiotic division take place?

Meiotic division takes place in the reproductive cells of the organisms.

  • How many types are there in meiosis?

There are two types in meiosis – Meiosis-I, and Meiosis-II.

  • What is the advantage of meiosis?

Because of the process of meiosis, the genetic recombination from one generation to next is possible. It is a special cell division process.

Fertilizers Vs Manure

It is necessary to understand the difference between manure and fertilizers for a good farmer. Farmers, be it the small-scale farmers or the large-scale farmers, aim at maximizing their profit gained from the agricultural activities. And to get a better-quality crop from the farming, it is important to use good-quality fertilizers and manures. And these fertilizers and manures should also be eco-friendly in nature.

 Because, the use of chemical products may yield better results for a small period, but in long-term results, it can harm the fertility of the soil. Also, a balanced amount of manure and fertilizers should be used, as excessive use can also harm the crops and the soil.

Manuring and Fertilizers

Manure is a product added to provide essential nutrients to the crop. The process of adding chemical or natural manure is undertaken to benefit the crop. It helps in improving the capacity of holding water, aeration, and the texture of the farming soil.

Natural manure includes dead plant waste, decomposed organic substances, etc. Thus, manures are organic in nature and they are more preferable over chemical products. They can cause no harm to the crop or the soil.

Fertilizers are chemical compounds consisting of organic compounds, and considered as rich sources of plant nutrients. Fertilizers are commercial agricultural products that are manufactured in industries.

Though fertilizers are chemical, they should have a good amount of organic components, so that they will not cause any harm to the crop or the soil.

There are some other methods too, for the development of the crop. These are:


It is obtained earthworms and their activities on organic wastes. It is type f organic manure.

Crop rotation

This is an age-old method, in which rotation in the process of crop cultivation is done, in alternate years. It helps to increase the minerals in the soil.

Leguminous plants

Leguminous plants have bacteria required for nitrogen-fixing. So, these plants are selected for crop rotation to facilitate nitrogen-fixing.

Difference between Fertilizer and Manure

In order to differentiate fertilizers and manure, let’s have a look at some important basic points:

Fertilizers can either be artificial or natural products.Manures, unlike fertilizers, are a natural and organic substance.
Basically, fertilizers are some kind of essential chemicals, whose addition to the soil can increase its fertility. As a result, farmers can get a good crop.Manures are formed by the dead and decomposed remains of the animal and plants.
Fertilizers are produced in companies.One can produce or prepare manures in fields as well. They do not require factory manufacturing.
Fertilizers are not able to provide humus for the soil.Unlike fertilizers, manures are capable of providing humus to the soil.
Fertilizers have a very good amount of essential nutrients required for the plants.Manures lack a sufficient amount of plant nutrients.
Plants are able to absorb the fertilizers very quickly.Plants cannot absorb manure as quickly as the fertilizers.

Apart from these basic points, it is possible to differentiate between manure and fertilizers with some other points. When we talk about manure vs. fertilizer, it is to be noted that fertilizers are costly in comparison with manures. And manures are cost-effective, and they also don’t cause any harm to the nature, like fertilizers can do.

Frequently asked questions:

  1. Explain how fertilizers are different from manure.

Fertilizers are factory-made chemical compounds that provide rich nutrients to the soil and the crop. And, manure is added to the soil to increase its fertility and to make it yield better results.

  • What is manure and fertilizer?                   

Manure is an organic compound formed from the decomposed and dead organic substances of the plants and animals. It is useful to increase the fertility. On the other hand, fertilizers are chemically synthesized compounds, used to provide nutrients to the crops and soils. But they are beneficial because they contain organic compounds that are harmless to the nature.

  • What is the difference between manure and fertilizers?   

Manure is a natural substance whereas fertilizer is a chemical substance. Manure can be used as a fertilizer, but the reverse is not possible.

  • Is manure better than the fertilizer?

Depending upon the method in which they are formed, manure is considered to be better than the fertilizer. Because manure is a natural product, unlike the fertilizer. However, a limited or balance use of fertilizer can cause no harm.

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