What is Mutualism? write type and example.

Question:

What is Mutualism? write type and example.

Answer:

Mutualism:

The term mutualism can be simply defined as a relationship in which both species are mutually benefited. This relationship can either be within the species or between the two different species. The species with this relationship is termed as symbionts.

Mutual relationship is seen in all living organisms including human beings, animals, birds, plants and other microorganisms like bacteria, virus, and fungi. Mutualism is a sort of symbiosis.

Mutualism is a type of relationship between the host and a symbiont, where both organisms benefit and no one is harmed. This relationship may either continue for longer or for shorter-term. The term mutualist is used to indicate the small partner and the host are the other partners present in the Mutualism.

For example, Ants live and feed on the nectar of acacia trees. Here ants are the mutualist and acacia trees is the host.

The acacia tree provides home and food for the ants. As they have hollow huge thorns – homes for the ants and yellow swellings on the leaves- food for the ants. In reverse ants acts a guard attacking insects and protects the tree from grazing animals.

Types of Mutualism

There are five types of Mutualism.

Obligate Mutualism

In obligate mutualism the relationship between two species, in which both are completely dependent on each other. Most of the symbioses and some non-symbiotic are the best examples of obligate mutualism

For example Yucca plant and the moth.

The yucca plant, the habitat of the dry and arid climate of the southwestern United States. The flower of the yucca plant relies on the moth for the pollination process. In turn, the moth is benefited by laying its eggs on the flower and feeding the larvae with the seeds.

Facultative Mutualism

In facul­tative mutualism, the partners may coexist without a depending on each other. They, how­ever, form a diffuse relationship involving a varying mixture of species.

For example Honeybees and plants.

Honey bees visit many different plants species for the nectar from the flower and these plants will be visited by the number of the insect as pollinators for pollination.

Trophic Mutualism

In trophic mutualism, the partners are specialized in complemen­tary ways to obtain energy and nutrients from each other.

For example The cows and the bacteria.

Cows cannot digest the plant’s cellulose. The bacteria present in the rumens of cows helps in digesting plants cellulose. In reverse bacteria gets food and warm environment, which is required for their growth and development.

Defensive Mutualism

In defensive mutualism, one partner receives food and shelter and in return, it helps the partner by defending against the herbivores or predators or parasites.

For example The aphids and the ants.

 The aphids produce honeydew to the ants, which is carried to their nests at night for protecting them from the predators and escort. These aphids are carried back to the plant the next morning. In return, ants are benefited by assembling the aphid’s eggs and storing in their nest chambers to survive the cold winter months.

Dispersive Mutualism

In dispersive mutualism, one partner receives food in return for helping flower in transferring their pollen.

For example Honeybees and the Plants.

Honey bees travel from one flower to another in search of nectar from the flower which is required to prepare honey, in return plants are benefited by the pollination as the honey bee spread the pollen from one plant to another.

Examples Of Mutualism

Following are the important examples of mutualism:

Humans and Plants

The human requires oxygen for life and plants use the carbon dioxide for photosynthesis. Here both human and plants are mutually benefited. Humans use the oxygen given by the plants. In return, plants use carbon dioxide, which is exhaled by the Humans.

Oxpeckers and Rhinos

The bird oxpecker lives on the rhino and removes all bugs and parasites on the animal skin by eating them. The Rhino provides the bird with food and in return, the bugs removed from the skin of the rhino. Both rhino and the oxpecker is benefited.

Write theory of evolution.

Question:

Write theory of evolution.

Answer:

Charles Darwin, an English naturalist of the 19th century made an extensive study of nature for over 20 years. He collected the observations on animal distribution and the relationship between the living and extinct animals and finally found that the present living animals share similarities to some extent not only between them but also with the other species that existed millions of years ago and among which some have become extinct.

Charles Darwin is known as the father of evolution due to his contribution to the establishment of the theory of evolution. His theory helped in removing all the conventional old believes which said that the formation of various species was a supernatural phenomenon or act of the Almighty. Darwin’s evolutionary theory of natural selection gave a more rational explanation of the formation of new species. As per natural selection, various species originated from a single species as a result of adaptation to the changing environment.

The Theory of Evolution

Darwin had the following ideas regarding the theory of natural selection:

• Species keep on evolving or changing with time. As the environment changes, the requirements of an organism also change and they adapt to the new environment. This phenomenon of changing over a period of time as per the natural requirements is called adaptation.
• As per Darwin’s theory, only the superior changes are naturally selected and the inferior ones are eliminated. Thus, not all adaptations contribute to progressive evolution. For example, people living in tropical countries have more melanin in their body to protect them from the sunlight.
• Almost all organisms share common ancestry with some organism. According to Darwin, all organisms had one common ancestor at some point in time and kept on diverging ever since. His evolutionary theories support the convergent theory and divergent theory of evolution with examples.
• He also studied that the birds of Galapagos Island (Darwin’s finches) developed different beaks as per the availability of the food. This proved adaptive radiation. Similarly, he also observed the Australian Marsupials which showed a number of marsupials emerging from an ancestor.
• According to Charles Darwin, evolution is a very slow and gradual process. He concluded that evolution took place over a very long period of time. As we talk about the time period in evolution we usually refer to billions of years. The generation of a species from another takes a long period of time. It is a very steady process as the changes and adaptation take a long time to stabilize and give rise to a new species.

Natural selection takes place in four different ways as follows:

1. Variation – The changes accumulated over a period of time in an organism usually give rise to a new species.
2. Inheritance – It is the passing on of the variations over generations which ultimately leads to speciation.
3. A high rate of growth of population – This gives rise to more number of organisms being reproduced by a species than the environment can support.
4. Differential survival and reproduction – The superior variations lead to the survival of a particular organism and the inferior or negative variations leads to extinction. The superior variations are the ones inherited during reproduction.

Write causes of Leprosy, also write symptoms and treatment.

Question:

Write causes of Leprosy, also write symptoms  and treatment.

Answer: 

Causes of Leprosy

The pathogen Mycobacterium laprae, the causes leprosy

This disease is caused by bacteria, “Mycobacterium leprae” which is slow-growing. Leprosy is also termed as Hansen’s disease after the name of the scientist – Dr Gerhard Henrik Armauer Hansen who discovered this infectious disease in the year 1873.

Symptoms of Leprosy

Leprosy firstly affects the skin and then moves on to nerves present outside the brain and spinal cord which is known as the peripheral nerves.

Although it takes three to five years for these symptoms to appear after coming in contact with the bacteria, in some cases, symptoms appear after 20 years of being infected.

The time period between being exposed and the appearance of symptoms is known as the incubation period. If this period increases then, it is very difficult for doctors to diagnose the disease.

Following are some of the symptoms of leprosy:

• Severe pain.
• Bleeding Nose.
• Growth on skin.
• Enlarged nerves.
• Stiff, dry, and thick skin.
• Ulcers on the soles of the feet.
• Paralysis or muscle weakness.
• Non-sensitive lesions on the body.
• Numbness in hands, arms, feet, and legs.
• Eye problems that might even cause blindness.

Diagnosis of Leprosy

The diagnosis of leprosy is based on signs and symptoms. A skin test or a skin lesion biopsy is advised by the doctors to detect the disease.

Treatment of Leprosy

Leprosy treatment fully depends on the type of leprosy the patient is suffering from. Antibiotics are used by doctors to treat the infection. Long-term treatment includes two or more antibiotics which will carry from 6 months to a year.

People suffering from severe leprosy may need to take antibiotics for a longer time period. But, these antibiotics are unable to treat the nerve damage. There are some anti-inflammatory drugs that are used to control nerve pain and severe damage caused by leprosy.

What is Leprosy? list out the type of Leprosy.

Question:

What is Leprosy? list out the type of Leprosy.

Answer:

Leprosy is a disease that causes severe, scarring skin sores and nerve damage in the limbs. Leprosy disease has affected people on every continent. Leprosy is actually not that infectious but it spreads when a healthy person comes in regular and close contact with mouse droplets and leprosy patient. Children get more affected by this disease than adults. Almost, 180000 people all over the world get infected with leprosy.

The Leprosy disease mainly affects the peripheral nerves, skin, upper respiratory tract and the eyes. The most prevalent possibility of transmission is through the respiratory route. Leprosy is also transmitted through insects.

Let us have a detailed look at the Leprosy disease, different types of leprosy, causes of Leprosy, symptoms and treatment of Leprosy disease.

Types of Leprosy

There are six types of leprosy and are mainly classified based on the severity of symptoms, which include- Intermediate, Tuberculoid, Borderline tuberculoid, Mid-borderline, Borderline and Lepromatous leprosy.

Let us know more about each of them in detail.

Intermediate Leprosy

It is the earliest stage of leprosy. In this stage, patients suffer from flat lesions which may heal by themselves without progressing in case of strong immunity.

Tuberculoid Leprosy

It is the mild and less serious type of leprosy. People suffering from this disease have some patches of flat and pale-colored skin and have no sensation in the affected area because of nerve damage. This is less infectious than other forms. This infection heals on its own, or it can persist and progress to a more severe form.

Borderline tuberculoid Leprosy

The symptoms at this stage are quite similar to the tuberculoid but the infections may be quite smaller and more in number which may continue and revert to tuberculoid, or to any other advanced form.

Mid-borderline Leprosy

The sign and symptoms of this stage are quite similar to the Borderline tuberculoid leprosy. This includes reddish plaques with the numbness which may regress or progress to another form.

Borderline Leprosy

This type of leprosy is a cutaneous skin condition and the main symptoms include multiple wounds or scars including plaques, flat, raised bumps that may continue or regress.

Lepromatous Leprosy

It is considered a more severe type of disease with many lesions with bacteria. The affected region is full of bumps, numbness, muscle weakness and rashes. Other symptoms include limb weakness, hair loss and other body parts such as kidneys, nose and male reproductive system are also affected. It is more infectious than tuberculoid leprosy which never regresses. 

Write Symptoms of Sleeping Sickness, also write prevention.

Question:

Write Symptoms of Sleeping Sickness, also write prevention. 

Answer:

Symptoms of Sleeping Sickness

A lot of changes occur in the body after the infection. Few symptoms of sleeping sickness are listed below:

• An unclear speech.
• Seizures.
• Irritation.
• Swelling of the brain.
• Swelling of the lymph nodes.
• Causes weakness in the body.
• Feeling of sleeplessness.
• Severe sweating.
• Formation of red sores on places of infection.
• Severe fever conditions.
• Mood changes.
• Skin Rashes.
• Severe headaches.
• Develop severe pain in the joint.
• Personality changes.
• Feel difficulty in walking and etc.

Sleeping Sickness Prevention

Early recognition of the disease might help to avoid the difficulty and major risks. Some of the prevention and treatment measures include:

• Early treatment of the infected persons, including the person showing no symptoms.
• Using insecticides to protect oneself against the bite of Tsetse fly.
• By maintaining clearings around the villages and also residential areas.
• Use of repellents or fly traps to stay away from the flies.

 

Write Life Cycle and examples of Pteridophyta.

Question:

Write Life Cycle and examples of Pteridophyta.

Answer:

Pteridophytes show alternation of generations. Their life cycle is similar to seed-bearing plants, however, the pteridophytes differ from mosses and seed plants as both haploid gametophyte and diploid sporophyte generations are independent and free-living. The sexuality of pteridophytic gametophytes can be classified as follows:

1. Dioicous: the individual gametophyte is either a male producing antheridia and sperm or a female producing archegonia and egg cells.
2. Monoicous: every individual gametophyte may produce both antheridia and archegonia and it can function both as a male as well as a female.
3. Protandrous: the antheridia matures before the archegonia.
4. Protogynous: the archegonia matures before the antheridia.

Pteridophyta Examples

Following are the important examples of Pteridophyta:

• Whisk Fern
• Dicksonia
• Selaginella
• Lycopodium
• Equisetum
• Pteris
• Dryopteris
• Adiantum
• Man fern
• Silver fern

 

Write Pteridophyta Characteristics.

Question: 

Write Pteridophyta Characteristics.

Answer:

1. Pteridophytes are considered as the first plants to be evolved on land:

It is speculated that life began in the oceans, and through millions of years of evolution, life slowly adapted on to dry land. And among the first of the plants to truly live on land were the Pteridophytes.

2. They are cryptogams, seedless and vascular:

Pteridophytes are seedless, and they reproduce through spores. They contain vascular tissues but lack xylem vessels and phloem companion cells.

3. The plant body has true roots, stem and leaves:

They have well-differentiated plant body into root, stem and leaves.

4. Spores develop in sporangia:

The sporangium is the structures in which spores are formed. They are usually homosporous (meaning: one type of spore is produced) and are also heterosporous, (meaning: two kinds of spores are produced.)

Read More: Sporulation

5. Sporangia are produced in groups on sporophylls:

Leaves that bear the sporangia are termed as sporophylls. The tip of the leaves tends to curl inwards to protect the vulnerable growing parts.

6. Sex organs are multicellular:

The male sex organs are called antheridia, while the female sex organs are called archegonia.

7. They show true alternation of generations:

The sporophyte generation and the gametophyte generation are observed in Pteridophytes. The diploid sporophyte is the main plant body.

Write Pteridophyta Classification.

Question:

Write Pteridophyta Classification.

Answer:

Pteridophyta is classified into four main classes:

Psilopsida

• They are the most primitive.
• The stem is photosynthetic and dichotomously branched.
• Rhizoids are present.
• Leaves are mostly absent.
• The sporophyte is homosporous synangium.
• Examples- Psilotum and Tmesipteris.

Lycopsida

• They are commonly known as club moss.
• Well-differentiated plant body with adventitious root, stem, rhizophores and leaves.
• The sporophyte is homosporous or heterosporous.
• Examples- Selaginella, Lycopodium.

Sphenopsida

• Commonly known as horsetail.
• Well-differentiated plant body with roots arising from nodes of the underground rhizome, stem and scaly leaves.
• Homosporous, sporangia are borne on strobili.
• Examples- Equisetum.

Pteropsida

• Commonly known as a fern.
• Well-differentiated plant body with roots, stem and leaves.
• The sporophyte is homosporous or heterosporous.
• Antherozoids are multiflagellate.
• Examples- Pteris, Dryopteris, Adiantum

 

Write Factors of Modern Synthetic Theory of Evolution.

Question: 

Write Factors of Modern Synthetic Theory of Evolution.

Answer:

There are some factors describing the modern theory of synthetic evolution which are as explained below-

In addition to these reactions, the other factors affecting the working of the process are the migration of the individuals from one form of the population to other, hybridization between the races of species increases the genetic variability of the popu­lation.

Recombination or Variation

Recombination of the new genotypes from the existing genes. The gene combinations having same indi­viduals with two kinds of alleles, mixing of the chromosomes during sexual reproduc­tion of two parents produce new individuals, an exchange of the chromosomal pairs of alleles during the meiosis which is called crossing overproduce the new form of gene combinations. Chromosomal mutations like deletion, inversion, duplication, translocation, polyploidy result in the recombination.

Mutation

The changes that occur in the gene due to phenotypic effect differential as the mutation. This produces a variety of changes that may be harmful. Many of the mutant forms of genes are recessive to the normal genes in a homozygous condition. These mutations cause variations in off springs.

Heredity

The transmission occurring in the variations from the parents to their off springs is a primary mechanism in the evolution. The organisms which possess hereditary properties are favored in the struggle for the existence. By this, the off springs benefit from the characteristics of parents.

Natural selection

Natural selection produces a change in the frequency of the genes from one generation to the other favouring the differential form of the reproduction. The natural selection process creates an adaptive relation between the environment and the population through various combinations of genes.

Isolation

It is one of the significant factors responsible for the synthetic theory of evolution. The isolation helps in preventing the interbreeding of related organisms which is a reproductive form of isolation.

What is plant tissue culture? also write procedure, type and uses of plant tissue culture.

Question:

What is plant tissue culture? also write procedure, type and uses of plant tissue culture.

Answer:

Plant tissue culture was a new addition to the methods of plant breeding that developed around the 1950s. Since the conventional breeding techniques could not fulfil the required demand of crops, tissue culture came around as a grand leap in breeding practices. It makes use of parts of a plant to generate multiple copies of the plant in a very short duration. The technique exploits the property of totipotency of plant cell which means that any cell from any part of the plant can be used to generate a whole new plant.

Types of Plant tissue culture

1. Seed Culture
2. Embryo Culture
3. Callus Culture
4. Organ Culture
5. Protoplast Culture
6. Anther Culture

Procedure of Plant tissue culture

The part(s) of the plant used for culturing is known as explants. The explants are cultured in-vitro on a nutrient medium that caters to fulfil its nutritional requirements. The nutrient medium must provide the following:-

1. Macronutrients – This includes elements like nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sulfur (S) which is required for proper growth and morphogenesis.
2. Micronutrients – Elements like iron (Fe), manganese (Mn), zinc (Zn) etc., which are also crucial to the growth of tissues.
3. Carbon or Energy source – This is one of the most crucial ingredients of the nutrient media. Sucrose is the most widely used carbon source among other carbohydrates that serve to provide C, H, and O.
4. Vitamins, amino acids, and other inorganic salts.

Apart from these, the culture media also serves as a medium for supplying phytohormones or plant growth regulators to the issues which bring about their morphogenesis as per requirement. The tissues of the explants first lose their specificity to form a hard brown lump known as callus. The callus then splits to develop a plant organ or a whole new plant depending upon the quantity and composition of phytohormones supplied. The entire process requires strict aseptic conditions to be maintained at all times as a single contamination can ruin an entire batch of plants.

Uses of Plant tissue culture

Tissue culture is used to develop thousands of genetically identical plants from one single parent plant known as somaclones, and this process is known as micropropagation. The method offers an advantage over other methods as it can be used to develop disease free plants from disease-rode plants by using their meristems (apical and axillary) as explants.

Since this method produces new plantlets by the score of thousands, it has been used extensively for the production of commercially important plants including food plants like tomato, banana, apple etc. The most notable example of the application of micropropagation was observed in the farming of orchids as it rose exponentially due to the availability of millions of plantlets due to tissue culture methods.

For a more detailed understanding of plant tissue 

What is Ecological Succession? also write examples and type of ecological succession.

Question: 

What is Ecological Succession? also write examples and type of ecological succession.

Answer:

Ecological succession is the steady and gradual change in a species of a given area with respect to the changing environment. It is a predictable change and is an inevitable process of nature as all the biotic components have to keep up with the changes in our environment.

The ultimate aim of this process is to reach equilibrium in the ecosystem. The community that achieves this aim is called a climax community. In an attempt to reach this equilibrium, some species increase in number while some other decrease.

In an area, the sequence of communities that undergo changes is called sere. Thus, each community that changes is called a seral stage or seral community.

All the communities that we observe today around us have undergone succession over a period of time since their existence. Thus, we can say that evolution is a process that has taken place simultaneously along with that of ecological succession. Also, the initiation of life on earth can be considered to be a result of this succession process.

If we consider an area where life starts from scratch by the process of succession, it is known as primary succession. However, if life starts at a place after the area has lost all the life forms existing there, the process is called secondary succession.

It is obvious that primary succession is a rather slow process as life has to start from nothing whereas secondary succession is faster because it starts at a place which had already supported life before. Moreover, the first species that comes into existence during primary succession is known as pioneer species.

Types of Ecological Succession

These are the following types of ecological succession:

Primary Succession

Primary succession is the succession that starts in lifeless areas such as the regions devoid of soil or the areas where the soil is unable to sustain life.

When the planet was first formed there was no soil on earth. The earth was only made up of rocks. These rocks were broken down by microorganisms and eroded to form soil. The soil then becomes the foundation of plant life. These plants help in the survival of different animals and progress from primary succession to the climax community.

If this primary ecosystem is destroyed, secondary succession takes place.

Secondary Succession

Secondary succession occurs when the primary ecosystem gets destroyed. For eg., a climax community gets destroyed by fire. It gets recolonized after the destruction. This is known as secondary ecological succession. Small plants emerge first, followed by larger plants. The tall trees block the sunlight and change the structure of the organisms below the canopy. Finally, the climax community arrives.

Cyclic Succession

This is only the change in the structure of an ecosystem on a cyclic basis. Some plants remain dormant for the rest of the year and emerge all at once. This drastically changes the structure of an ecosystem.

Seral Community

“A seral community is an intermediate stage of ecological succession advancing towards the climax community.”

A seral community is replaced by the subsequent community. It consists of simple food webs and food chains. It exhibits a very low degree of diversity. The individuals are less in number and the nutrients are also less.

There are seven different types of series:

Examples of Ecological Succession

Following are the important examples of ecological succession:

Acadia National Park

This national park suffered a huge wildfire. Restoration of the forest was left to nature. In the initial years, only small plants grew on the burnt soil. After several years, the forest showed diversity in tree species. However, the trees before the fire were mostly evergreen, while the trees that grew after the fire were deciduous in nature.

Ecological Succession of Coral Reefs

Small coral polyps colonize the rocks. These polyps grow and divide to form coral colonies. The shape of the coral reefs attracts small fish and crustaceans that are food for the larger fish. Thus, a fully functional coral reef exists.

Write Dicotyledonous and Monocotyledonous Leaves.

Question: 

Write Dicotyledonous and Monocotyledonous Leaves.

Answer:

Dicotyledonous and Monocotyledonous Leaves

Dicot Leaf

Dicotyledonous leaf shows reticulate venation.

• Lamina consists of epidermis, mesophyll and vascular system.
• The epidermis is covered by cuticle and stomata; abaxial epidermis (lower surface) possesses more stomata than adaxial epidermis (upper surface). Sometimes adaxial epidermis lack stomata.
• Mesophyll, (parenchymatous cells) composed of the palisade and spongy parenchyma is present in between the adaxial epidermis and abaxial epidermis.
• The chloroplasts present in mesophyll perform photosynthesis in leaves.
• Vascular bundles are surrounded by bundle sheath cells and form the veins and midrib.

Monocot Leaf

Monocotyledonous leaves are characterized by parallel venation. The anatomy of a monocot leaf includes:

• Both adaxial epidermis and abaxial epidermis bear stomata.
• There is no differentiated palisade and spongy parenchyma of the mesophyll.
• Bulliform cells are present, which is developed from adaxial epidermal cells and the veins.
• Bulliform cells are large, void cells which are responsible for the curling of leaves for minimal loss of water.

Write Dicotyledonous and Monocotyledonous Roots.

Question:

Write Dicotyledonous and Monocotyledonous Roots.

Answer:

Dicot Root

• Dicot plants have the taproot system.
• The outermost layer is called the epidermis. The epidermal cells sometimes project out which appear as the root hairs.
• The epidermis is followed by the multi-layered cortex, loosely made of the parenchyma cells with intercellular spaces.
• The inner layer of the cortex is called endodermis, which is tightly packed by the barrel shaped-cells.
• Endodermis is followed by pericycle, which are a few layers of thick-walled parenchyma cells.
• In dicots, the central pith is not distinct.
• There are two to four xylem and phloem.
• The xylem and phloem are remarked by a layer of parenchymatous cells known as conjunctive tissue.

During secondary growth, the cambium separates the xylem and phloem. Pericycle, vascular bundles and pith fuse to form stele in dicots.

Monocot Root

Monocot roots do not show much difference in the anatomy from that of the dicot roots.

• Monocot plants possess an adventitious root system.
• As in the dicots, the epidermis forms the outermost layer, followed by cortex, pericycle, endodermis, vascular bundles (xylem and phloem) and pith (random order).
• Pith is conspicuous and large.
• The number of xylem in a monocot is six or more.
• Secondary growth is not seen in the monocot plants.

Write Dicotyledonous and Monocotyledonous Stem.

Question: 

Write Dicotyledonous and Monocotyledonous Stem.

Answer

Dicot Stem

The dicotyledonous stem is usually solid. The transverse section of a typical young dicotyledonous stem consists of the following parts:

• The epidermis is the outermost protective layer, which is covered with a thin layer of cuticle.
• Epidermis possesses trichomes and a few stomata.
• Cortex is multi-layered cells sandwiched between epidermis and pericycle.
• The outer layer, hypodermis (collenchymatous cells), the cortical layers (parenchymatous cells) and the inner layer, endodermis together make up the three subzones of the cortex.
• Next to endodermis is the pericycle, which is constituted of semi-lunar patches of sclerenchyma.
• ‘Circled’/ ‘ring’ arrangement of vascular bundles is present only in dicot stem.
• The Vascular bundle is conjoint, open and with endarch protoxylem.
• Pith is evident and is made of parenchymatous cells.

Monocot Stem

Monocot stem is usually hollow with no secondary growth. The anatomy of monocot and dicot stem are similar, however, some notable differences are as follows:

• The hypodermis of the cortex in monocots is made of sclerenchymatous cells.
• Vascular bundles are numerous, but scattered, conjoint and closed, surrounded by the ground tissue.
• Phloem parenchyma is absent.

Write major classes of Biomolecules.

Question:

Write major classes of Biomolecules.

Answer:

There are four major classes of Biomolecules –  Carbohydrates, Proteins, Nucleic acids and Lipids. Each of them is discussed below.

Carbohydrates

Carbohydrates are chemically defined as polyhydroxy aldehydes or ketones or compounds which produce them on hydrolysis. In layman’s terms, we acknowledge carbohydrates as sugars or substances that taste sweet. They are collectively called as saccharides (Greek: sakcharon = sugar). Depending on the number of constituting sugar units obtained upon hydrolysis, they are classified as monosaccharides (1 unit), oligosaccharides (2-10 units) and polysaccharides (more than 10 units). They have multiple functions’ viz. they’re the most abundant dietary source of energy; they are structurally very important for many living organisms as they form a major structural component, e.g. cellulose is an important structural fibre for plants.

Proteins

Proteins are another class of indispensable biomolecules, which make up around 50per cent of the cellular dry weight. Proteins are polymers of amino acids arranged in the form of polypeptide chains. The structure of proteins is classified as primary, secondary, tertiary and quaternary in some cases. These structures are based on the level of complexity of the folding of a polypeptide chain. Proteins play both structural and dynamic roles. Myosin is the protein that allows movement by contraction of muscles. Most enzymes are proteinaceous in nature.

Nucleic Acids

Nucleic acids refer to the genetic material found in the cell that carries all the hereditary information from parents to progeny. There are two types of nucleic acids namely, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The main function of nucleic acid is the transfer of genetic information and synthesis of proteins by processes known as translation and transcription. The monomeric unit of nucleic acids is known as nucleotide and is composed of a nitrogenous base, pentose sugar, and phosphate. The nucleotides are linked by a 3’ and 5’ phosphodiester bond. The nitrogen base attached to the pentose sugar makes the nucleotide distinct. There are 4 major nitrogenous bases found in DNA: adenine, guanine, cytosine, and thymine. In RNA, thymine is replaced by uracil. The DNA structure is described as a double-helix or double-helical structure which is formed by hydrogen bonding between the bases of two antiparallel polynucleotide chains. Overall, the DNA structure looks similar to a twisted ladder.

Lipids

Lipids are organic substances that are insoluble in water, soluble in organic solvents, are related to fatty acids and are utilized by the living cell. They include fats, waxes, sterols, fat-soluble vitamins, mono-, di- or triglycerides, phospholipids, etc. Unlike carbohydrates, proteins, and nucleic acids, lipids are not polymeric molecules. Lipids play a great role in the cellular structure and are the chief source of energy.

Write Difference between Red Blood Cells and White Blood Cells.

Question:

Write Difference between Red Blood Cells and White Blood Cells.

Answer:

Difference between Red Blood Cells and White Blood Cells:

The significant differences between red blood cells and white blood cells are as follows:

RBC – Red Blood Cells	WBC – White Blood Cells
Red blood cells are called Erythrocytes.	White Blood Cells are called Leucocytes or Leukocytes.
RBCs have a bi-concave disc shape	WBCs have an irregular shape.
Size varies from 6 – 8 µm in diameter.	Size varies from 12 – 17 µm in diameter.
The lifespan of RBC is about 120 days.	The lifespan of WBC is around 12-20 days after which they are destroyed in the lymphatic system
Red blood cells do not have a nucleus on maturity.	WBCs are characterized by the presence of a large central nucleus.
Due to the presence of haemoglobin, these cells appear red in colour.	These cells are colourless, as they do not have any pigment.
Only one type of RBC exists.	Different types of WBCs are found in the blood such as neutrophils, B lymphocytes, T lymphocytes, monocytes, basophils, eosinophils.
They help in the transport of respiratory gases to different parts of the human body	They help in producing antibodies to fight against disease-causing microbes.
RBCs are produced in the red bone marrow	These cells are produced in the red bone marrow, lymph nodes, and spleen.
The components of red blood cells are haemoglobin.	The components of white blood cells are antibodies with the presence of MHC (major histocompatibility complex) antigen cell markers.
These cells make up around 36-50% of human blood.	They make up around 1% of the human blood.
RBC count: 5 million/ mm³ of blood.	WBC count: 7000–8000/mm³ of blood.
The process of formation of RBC is known as erythropoiesis.	The process of formation of WBC is known as leukopoiesis.
These cells move between the cardiovascular systems.	These cells move between the cardiovascular and lymphatic systems.
Low count of RBCs results in Anaemia.	Low count of WBCs results in Leukopenia.

Write Features and Significance of Meiosis.

Question:

Write Features and Significance of Meiosis.

Answer:

Features of Meiosis

• It results in the formation of four daughter cells in each cycle of cell division.
• The daughter cells are identical to the mother cell in shape and size but different in chromosome number.
• The daughter cells are haploid.
• Recombination and segregation take place in meiosis.
• The process occurs in the reproductive organs and results in the formation of gametes.
• The process is divided into two types-Meiosis-I reduces the chromosome number to half and is known as reductional division. Meiosis-II is just like the mitotic division.

Significance

1. Meiosis is responsible for the formation of sex cells or gametes that are responsible for sexual reproduction.
2. It activates the genetic information for the development of sex cells and deactivates the sporophytic information.
3. It maintains the constant number of chromosomes by halving the same. This is important because the chromosome number doubles after fertilization.
4. In this process independent assortment of maternal and paternal chromosomes takes place. Thus the chromosomes and the traits controlled by them are reshuffled.
5. The genetic mutation occurs due to irregularities in cell division by meiosis. The mutations that are beneficial are carried on by natural selection.
6. Crossing over produces a new combination of traits and variations.