Smart Lecture 16 To 20 Notes For BS Biological Science 2022 Free Download

Smart Lecture 16 To 20 Notes For BS Biological Science 2022 Free Download

Smart Lecture 16 To 20 Notes For BS Biological Science 2022 Free Download.

Smart Lecture 16 To 20 Notes For BS Biological Science 2022 Free Download
Smart Lecture 16 To 20 Notes For BS Biological Science 2022 Free Download

Lecture # 16


  • “Enzymes can be defined as biological polymers that catalyze e biochemical reactions.” 
  • Majority of enzymes are proteins with catalytic capabilities crucial to perform different.

Enzyme Structure

  • Enzymes are a linear chain of amino acids, which give rise to a three-dimensional structure. The sequence of amino acids species the structure, which in turn identifies the catalytic activity of the enzyme. Upon heating, enzyme’s structure denatures, resulting in a loss of enzyme activity, that typically is associated with temperature.

The basic mechanism of enzyme action is to catalyze the chemical reactions, which begins with the binding of the substrate with the active site of the enzyme. This active site is a specific area that combines with the substrate.

Factors Affecting Enzyme Activity

  • The conditions of the reaction have a great impact on the activity of the enzymes. Enzymes are particular about the optimum conditions provided for the reactions such as temperature, pH, alteration in substrate concentration, etc.

Temperature and pH

  • Temperature and pH Enzymes require an optimum temperature and pH for their action. The temperature or pH at which a compound shows its maximum activity is called optimum temperature or optimum pH, respectively.
  • Generally, an optimum pH for enzymes is considered to be ranging between 5 and 7.

Active site

  • Enzymatic catalysis depends upon the activity of amino acid side chains assembled in the active center. Enzymes bind the substrate into a region of the active site in an intermediate conformation.
  • Often, the active site is a cleft or a pocket produced by the amino acids which take part in catalysis and substrate binding.

Concentration and Type of Substrate

  • Enzymes have a saturation point, i.e., once all the enzymes added are occupied by the substrate molecules, its activity will be ceased.  When the reaction begins, the velocity of enzyme action keeps on increasing on further addition of substrate.

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Lecture # 17


What is Immunity?

  • Immunity is the ability of the body to defend itself against disease-causing organisms. Everyday our body comes in contact with several pathogens, but only a few results into diseases. The reason is, our body has the ability to release antibodies against these pathogens and protects the body against diseases. This defense mechanism is called immunity.


  • “The study of the immune system, the cell-mediated and humor al aspects of immunity and immune responses.
  • Immunology is a branch of the biology involved with the study of the immune system, components of the immune system, its biological processes, the physiological functioning of the immune system, types, its disorder and lot more.

Immune system

  • Immune System consists of different types of cells and organs which protect our body against pathogens. Pathogens are defined as everything that does not belong to our body, from parasites to fungi, bacteria, viruses, and haptens. Haptens are molecules that may cause an immune response when comes in contact with a protein.
  • All these cells and molecules are distributed in all the tissues of the body as well as lymphoid organs which eliminate or prevent microbial infectious diseases decrease the growth of tumors and starts the repairing process of damaged tissues.
  • The tissues and organs of the immune system act as security forces where cells act as the security guards while molecules act as the guns & bullets and use the communication system to protect you.

Types of Immunity

  • 1. Innate Immunity or Natural or Non-specific Immunity.

This type of immunity is present in an organism by birth. This is activated immediately when the pathogen attacks. Innate immunity includes certain barriers and defense mechanisms that keep foreign particles out of the body. Innate immunity refers to the body’s defense system. This immunity helps us by providing the natural resistance components including salivary enzymes, natural killer cells, intact skin and neutrophils, etc. which produce an initial response against the infections at birth prior to exposure to a pathogen or antigens.

  • 2. Acquired Immunity or Adaptive Immunity.

Acquired immunity or adaptive immunity is the immunity that our body acquires or gains over time. Unlike the innate immunity, this is not present by birth. The ability of the immune system to adapt itself to disease and to generate pathogenspecic immunity is termed as acquired immunity.. The main function of acquired immunity is to relieve the victim of the infectious disease and also prevent its attack in future.

Immunology and Diseases

Normally, the disease occurs because of fundamental defects in the immune system. In this situation, the immune system is challenged and evoke responses that damage cells and tissues rather than protecting. All the immunodeficiency diseases increase the risk of tumors and infections and are caused by malnutrition, gene mutations, and viruses – HI

Symptoms of Immune Dysfunction

  • Bowel disorders.
  • Parasite infections.
  • Candida overgrowth.
  • Allergies and Asthma.
  • Frequent colds.
  • Painful joints and muscles.
  • Herpes (cold sore) outbreak.

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Lecture # 18





According to the World Health Organization (WHO), one among 200 polio infections results in permanent paralysis and this disease has been eradicated thanks to the development of a polio vaccine.

Polio also called as Poliomyelitis. It is a viral disease that destroys the nerve cells present in the spinal cord, causing paralysis or muscle weakness to some parts of the body. It is a contagious disease affecting the nervous system and is caused by Picornaviridae – a poliovirus.

Types Of Polio

1) Subclinical: This type of polio do not experience any symptoms as this does not affect the central nervous system – the brain and spinal cord. 95 per cent of polio cases identified are usually subclinical.

2) Non-paralytic: This type of polio does affect the central nervous system, but does not result in paralysis.

3) Paralytic: This is the most serious and rarest form of polio as it results in full or partial paralysis in the patient. Three types of paralytic polio are –

  • Spinal Polio – As the name suggests, it affects the spine.
  • Bulbar Polio – It affects the brainstem.
  • Bulb spinal Polio – It affects the spine and brainstem.

Signs and Symptoms of Poliomyelitis

If a person is infected with Sub-clinical Polio then he can face the following symptoms

  • Headache.
  • Slight fever.
  • Sore and red throat.
  • General discomfort.
  • Vomiting.

The following are the symptoms of Non-paralytic Polio –

  • Fever.
  • A sore throat.
  • Vomiting.
  • Headache.
  • Fatigue.
  • Abnormal reflexes.
  • Stiffness and pain in arm and leg pain.
  • Problems with swallowing and breathing.
  • Back pain, particularly neck stiffness.
  • Muscle tenderness and spasms.

People with paralytic polio

  • Loss of reflexes.
  • Severe spasms and muscle pain.
  • Loose and floppy limbs.
  • Sudden paralysis.
  • Deformed limbs.


What is Diarrhea?

  • Diarrhea is a condition where an individual experience a high frequency of loose and watery stools. The term is derived from the Greek words “Día” and “Rhein”, meaning “flowing through”. Usually, it is not a life-threatening disease and the duration of its symptoms usually vary as there are many causal factors.

Types Of Diarrhea

  • Secretory diarrhea – Excess fluid is secreted into the intestines.
  • Osmotic diarrhea – Caused when too much water is drawn into the bowels.
  • Motility-related diarrhea – Where intestines are too active and transport intestinal contents with great speed so that there is not enough time to absorb water and electrolytes. This results in loose and watery stools. —
  • Collagenous colitis – In this condition, the intestinal lining is damaged so that it cannot absorb water and electrolytes.
  • Inflammatory diarrhea – Where intestines are damaged due to bacterial or fungal infections.

Causes Of Diarrhea

  • It is primarily caused when there is a reduction in the absorption of fluid by intestines or an increase in the secretion of fluid or speedy passage of stool through intestines.
  • Intestinal disease.
  • Diabetes.
  • Alcohol consumption.
  • Consuming food that affects the digestive system.
  • Surgery to the digestive system.
  • Radiation therapy.
  • Food poisoning.
  • Skin cancers.

Symptoms Of Diarrhea

  • Loose stools
  • Vomiting
  • Nausea
  • Cramps
  • The feeling of a bowel movement
  • Abdominal pain
  • Fever
  • Bloody stools (rare cases)

Treatment Of Diarrhoea

  • Generally, acute diarrhea will recede on its own, within 2 to 3 days without any treatment. But it is advised to consult the physician regardless.

Following are a few treatments that a doctor may suggest:

  • Antibiotics may be helpful if the symptoms are caused by bacterial or parasitic infections
  • Water that contains salt and electrolytes help in replacing the lost fluids
  • Medications that treat symptomatically.


What is Malaria?


  • Malaria is a mosquito-borne infectious disease caused by various species of the parasitic protozoan microorganisms called Plasmodium. Malaria is a disease that man has battled with for a long time. The first evidence of this protozoan came from mosquitoes preserved in amber nearly 30 million years ago.
  • Malaria was so prevalent during the Roman times that the disease is also called ‘Roman Fever’. Today, the credit for actually discovering the parasite is given to Charles Louis Alphonse Laveran, a French physician. He even won the Nobel Prize in 1907 for his findings.

Causes of Malaria

  • Bitten by a malarial vector (Anopheles Stephens)
  • Use of shared and infected syringes.
  • Organ transplantation.
  • Transfusion.
  • From an infected mother to her baby during birth.

Symptoms of malaria

  • Symptoms of malaria are exhibited within 7 to 18 days of being infected. Common symptoms include:
  • Fever, fatigue, chills, vomiting, and headaches
  • Diarrhoea, anemia and muscle pain
  • Profuse sweating and convulsions
  • Bloody stools.
  • In severe cases, malaria can be devastating; it can lead to seizures, coma and eventually, death.

Prevention of malaria

  • Malaria is one of the major causes of preventable death in the world today. It affects more than 500 million people worldwide and causes 1 to 2 million deaths every year. It is a tropical infectious disease and almost 90 per cent of the cases are from Sub-Saharan Africa.
  • There are two ways to deal with malaria – prevent the mosquito bite from happening ( preventative steps) or attack the parasites once they have infected the body.
  • The first method advocates the use of mosquito nets and mosquito repellent such as permethrin to prevent mosquitoes from biting.
  • The second form of treatment uses a chemical called Quinine present in the bark of a cinchona tree.
  • A form of drug chloroquine has proven very effective against malaria even though it is not a vaccine.

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Lecture # 19


Global Warming Definition

  • “Global warming is a gradual increase in the earth’s temperature generally due to the greenhouse effect caused by increased levels of carbon dioxide, CFCs, and other pollutants. “

Causes of Global Warming

  • Man-made Causes of Global Warming —Deforestation

Plants are the main source of oxygen. They take in carbon dioxide and release oxygen thereby maintaining environmental balance. Forests are being depleted for many domestic and commercial purposes. This has led to an environmental imbalance, thereby giving rise to global warming.

  • Use of Vehicles

The use of vehicles, even for a very short distance results in various gaseous emissions. Vehicles burn fossil fuels which emit a large amount of carbon dioxide and other toxins into the atmosphere resulting in a temperature increase.

  • Chlorofluorocarbon

With the excessive use of air conditioners and refrigerators, humans have been adding CFCs into the environment which affects the atmospheric ozone layer. The ozone layer protects the earth surface from the harmful ultraviolet rays emitted by the sun. The CFCs has led to ozone layer depletion making way for the ultraviolet rays, thereby increasing the temperature of the earth.

  • Industrial Development
  • With the advent of industrialization, the temperature of the earth has been increasing rapidly. The harmful emissions from the factories add to the increasing temperature of the earth.
  • Agriculture
  • Various farming activities produce carbon dioxide and methane gas. These add to the greenhouse gases in the atmosphere and increase the temperature of the earth.
  • Overpopulation
  • Increase in population means more people breathing. This leads to an increase in the level of carbon dioxide, the primary gas causing global warming, in the atmosphere.
  • Natural Causes of Global Warming
  • Volcanoes Volcanoes are one of the largest natural contributors to global warming. The ash and smoke emitted during volcanic eruptions goes out into the atmosphere and affects the climate.
  • Water Vapour Water vapour is a kind of greenhouse gas. Due to the increase in the earth’s temperature more water gets evaporated from the water bodies and stays in the atmosphere adding to global warming.
  • Forest Blazes Forest blazes or forest fires emit a large amount of carbon-containing smoke. These gases are released into the atmosphere and increase the earth’s temperature resulting in global warming.

Effects of Global Warming

  • Rise in Temperature

Global warming has led to an incredible increase in earth’s temperature. This has resulted in an increase in the melting of glaciers, which have led to an increase in the sea level.

  • Threats to the Ecosystem

Global warming has affected the coral reefs that can lead to a loss of plant and animal lives.

  • Climate Change

Global warming has led to a change in climatic conditions. There are droughts at some places and floods at some. This climatic imbalance is the result of global warming.

  • Spread of Diseases

Global warming leads to a change in the patterns of heat and humidity. This has led to the movement of mosquitoes that carry and spread diseases.

  • High Mortality Rates

Due to an increase in floods, tsunamis and other natural calamities, the average death toll usually increases. Also, such events can bring about the spread of diseases that can hamper human life.

  • Loss of Natural Habitat

A global shift in the climate leads to the loss of habitats of several plants and animals. In this case, the animals need to migrate from their natural habitat and many of them even become extinct. This is yet another major impact of global warming on biodiversity.

Lecture # 20


Ozone definition

  • “The ozone layer is a region in the earth’s stratosphere that contains high concentrations of ozone and protects the earth from the harmful ultraviolet radiations of the sun.”
  • It has the potential to absorb around 97-99% of the harmful ultraviolet radiations coming from the sun that can damage life on earth.
  • If the ozone layer was absent, millions of people would develop skin diseases and may have weakened immune systems.
  • However, scientists have discovered a hole in the ozone layer over the Antarctic.
  • The main reasons for the ozone hole are chlorofluorocarbons, carbon tetrachloride, methyl bromide and hydro chlorofluorocarbons.

Ozone Layer Depletion

  • “Ozone layer depletion is the gradual thinning of the earth’s ozone layer in the upper atmosphere caused due to the release of  chemical compounds containing gaseous bromine or chlorine from industries or other human activities.”
  • This happens when the chlorine and bromine atoms in the atmosphere come in contact with ozone and destroy the ozone molecules. One chlorine can destroy 100,000 molecules of ozone. It is destroyed more quickly than it is created.
  • Some compounds release chlorine and bromine on exposure to high ultraviolet light, which then contributes to the ozone layer depletion. Such compounds are known as Ozone Depleting Substances (ODS).
  • Chlorofluorocarbons are the most abundant ozone-depleting substance. It is only when the chlorine atom reacts with some other molecule, it does not react with ozone.
  • Montreal Protocol was proposed in 1987 to stop the use, production and import of ozone-depleting substances and minimize their concentration in the atmosphere to protect the ozone layer of the earth.

Effects Of Ozone Layer Depletion

  • Effects on Human Health

The humans will be directly exposed to the harmful ultraviolet radiations of the sun due to the depletion of the ozone layer. This might result in serious health issues among humans, such as skin diseases, cancer, sunburns, cataract, quick ageing and an weakened immune system.

  • Effects on Animals

Direct exposure to ultraviolet radiations leads to skin and eye cancer in animals.

  • Effects on the Environment

Strong ultraviolet rays may lead to minimal growth, flowering and photosynthesis in plants. The forests also have to bear the harmful effects of the ultraviolet rays.

  • Effects on Marine Life

Planktons are greatly affected by the exposure to harmful ultraviolet rays. These are higher in the aquatic food chain. If the planktons are destroyed, the organisms present in the lower food chain are also affected.

Solutions to Ozone Layer Depletion

  • Avoid Using Pesticides

Natural methods should be implemented to get rid of pests and weeds instead of using chemicals. One can use eco-friendly chemicals to remove the pests or remove the weeds manually.

  • Minimize the Use of Vehicles

The vehicles emit a large amount of greenhouse gases that lead to global warming as well as ozone depletion. Therefore, the use of vehicles should be minimized as much as possible.

  • Use Eco-friendly Cleaning Products

Most of the cleaning products have chlorine and bromine releasing chemicals that find a way into the atmosphere and affect the ozone layer. These should be substituted with natural products to protect the environment.

  • Use of Nitrous Oxide should be Prohibited

The government should take actions and prohibit the use of harmful nitrous oxide that is adversely affecting the ozone layer. People should be made aware of the harmful effects of nitrous oxide and the products emitting the gas so that its use is minimized at the individual level as well.

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