Evolutionary role of Cyanobacteria

Cyanobacteria are a group of bacteria .they are photosynthetic .they are aquatic and are also found in moist soils. they have bluish green colouration. they are also called blue green algae because they arep photosynthetic and aquatic like algae.actually they are not algae but bacteria.algae are eukaryotes but cyanobacteria are prokaryotes.evolutionary they are very important group of organisms .their fossils have been traced back to 3.5bilion years ago . during evolutionary history of Earth they played important role by converting the reducing environment of Earth to oxidizing.they added oxygen to the earth environment by their photosynthetic activity.this paved the way for origin of aerobic organisms.they also played important role in origin of plants .according to endosymbiotic theory somewhere in proterozoic or Cambrian era a cyanobacteria entered a eukaryotic cell.here it found shelter and by photosynthetic activity provided food and oxygen to host cell also.gradualy this cyanobacteria got modified into chloroplast.
By : Ashwani,biology teacher,Phagwara.

Diatoms

Diatoms are a group of algae.they are found in oceans, freshwater bodies and even on moist soil.
ecologically they are very important.they produce 20% of oxygen produced on Earth.they are of different shapes, sizes and colours. they belong to division ochrophyta and class bacillariophyceae.
diatoms are solitary they can occur as solitary organisms or they may be colonial.when colonial,they may firm ribbon shaped,star shaped or zigzag colonies. the size of a diatom ranges from 2to 200 micrometers.their number increases very rapidly.if adequate sunlight and nutrients are available their number can become double in 24 hours. they mainly multiply by binary fission.
on the basis of shape diatoms have been classified into two categories. one is centric diatoms .they are radially symmetrical. other one is pennate diatom. they are bilaterally symmetrical. the life span of a diatom is about 6days. their cell wall forms a colourful case around them due to which diatoms are also called jewels of the sea. their cell wall form case or shell around individual cell. this case is called frustule. it is made up of silica, exactly hydrated silicon dioxide.in waterbodies they are passively carried away by water currents hence fall under phytoplankton.they cannot swim. however male gametes of centric diatoms can swim .most of the diatoms float passively on the surface of water.some are benthic found attached to the benthic substrates.diatoms are able to synthesize their food by photosynthesis.they are mostly restricted to the euphotic zone where sunlight can penetrate.their shell is unique having to two halves, upper larger one is called epitheca and lower one is called hypotheca.when a diatom divides each daughter cell receives one half of shell that is one valve which acts as epitheca.the daughter individuals develop new hypotheca. as hpotheca is smaller in size the daughter cell which receives hypotheca of parent cell, remember this hypotheca will act as epitheca in daughter cell and it will develop new hypotheca which will be smaller than epitheca.in this way this daughter cell will be smaller than parent cell even after full growth.after repeated binary fission the size of diatom cell will go on decreasing.it has been seen that after some binary fission's the diatoms undergo auxospore phase in which they increase in size and produce gametes by meiosis. dead diatoms sink to bottom of oceans and their shells  form diatomaceous earth.it is rich in silica and is s dynamite stabilizer.

1. By: Ashwani, Biology Teacher, Phagwara.

Sickle Cell Anaemia : An Example of Balanced Polymorphism

Sickle cell anaemia is caused by defective hemoglobin gene. the persons homozygous for sickle cell anaemia condition have two abnormal genes, one on each homologous chromosome .such persons are likely to die in their childhood because of large number of abnormal RBCs. on the other hand persons heterozygous for sickle cell anaemia have 1 normal gene at 1 homologous chromosome and one abnormal gene at other homologous chromosome .such persons have both normal and abnormal RBCs.  Abnormal RBCs  become sickle shaped under low oxygen conditions . Heterozygotes have more chances of survival up to reproductive age. It has been found that the persons heterozygous for sickle cell trait can tolerate the infection of Malaria caused by plasmodium falciparum .actually the sickle shaped RBCs do not support erythrocytic schizogony of malaria parasite plasmodium falciparum. Hetrozygotes therefore do not suffer seriously from plasmodium falciparum infection. they have normal RBCs also which can carry oxygen. In certain parts of Africa where infection due to plasmodium falciparum is common sickle cell trait is also prevalent. the natural selection selected sickle cell trait because the heterozygous for this trait were more resistant than normal persons against malarial infection. this existence of two different types of traits or say alleles of a gene in a population  is called balanced polymorphism and this is due to the selection of heterozygotes  by nature because of selective advantage in survival.

Mad Cow Disease

Mad cow disease is a neurodegenerative disease of cattle. it is caused by prions. priors are the misfolded proteins . their normal form is present in the cells. abnormal misfolded form becomes infectious and is called prion. a prion converts same kind of normal protein into abnormally folded protein.these abnormally folded proteins aggregate to form plaques which are toxic to nerve cells and cause death of nerve cells.
the cases of this disease  were reported in UK and Canada in 1990s.at present this disease is near eradication .
cause of spread of this disease was feeding the cattle on meat and bone meal. if this meat and bone bone has come from infected cattle it can cause mad cow disease in the fed cattle.the chances are high if the cattle feeds on brain or spinal cord of infected cattle   .
the appearance of symptoms may take several months or some years.the symptoms include abnormal walking of cattle due to less of muscle control.abnormal behavior of cattle, cattle goes into coma and ultimately dies. this disease is also called bovine spongiform encephalopathy.
man can also get infected by eating meat of infected cattle. man gets variant Creutzfeldt Jakob Disease by the prions that cause mad cow disease in  cows. mad cow disease does not spread by consuming milk of infected cows.

By:Ashwani,bio-teacher ,Phagwara.

Epigenetics

Epigenetics simply means something above or on top of the genetics. it involves the study of all the mechanisms that  changes the expression of genes by turning them switch on or switch off. the structure of gene is not altered but just turning the genes switch on or off changes the expression of genes.one such mechanism is methylation of DNA bases which prevents the expression of that DNA. the modification in his histone proteins of chromosome that tightly squeeze DNA in chromosome will prevent the expression of that DNA.the modifications in histones that relax the DNAwill allow the expression of DNA.it is due to epigenetics that skin cells are different from brain cells and liver cells. all of these cells have same kind of genes but in different types of cells different genes are switched on and switched off which makes these cells unique and different from others. our environmental also effects the turning on and off of genes for example when we spend more time in sunlight the amount of melanin increase in skin. what we eat also affects the turning on and off of genes. for example eating sugar rich diet cause more formation of  insulin.our mental stage also effects the turning on and off of genes .stress causes formation of cortisone hormone..for formation of cortisone specific genes are switched on. switch on and switch off of genes is a normal thing in body of all living organisms,but when this mechanism occur abnormally it results in diseases like cancer and Alzheimer.

By: Ashwani, bio-teacher ,Phagwara.

Prions

prions cause several neurodegenerative diseases in humans and other mammals.prions are proteinaceous infectious agents.they don't have any nucleic acid.this is a unique thing about prions. all the known pathogens like bacteria,viruses and others all have nucleic acid.prions retain their ability to infect even after treatment with ultraviolet radiations or other treatments that destroy nucleic acid.scientists have discovered that prions are the misfolded proteins with abnormal structure .when this abnormal protein binds to same type of normal protein it induce the latter to change its conformation . the newly distorted protein then induces the misfolding in other similar proteins. in this way it become a chain reaction. prions cause mad cow disease also known as bovine spongiform encephalopathy. scientists believe that infected cows may transmit infection to humans .it humans this infection causes CJD that is Creutzfeldt-Jakob disease.the process by which change in structure of protein occur is not clear and research is going on to understand the mechanism .in CJD disease scientists have discovered spongy structure of Brain in dead victims.this sponginess is caused due to holes in brain due to cell death . scientists believe that abnormal shaped protein becomes toxic to cell and causes cell death.prions can be transmitted by eating infected part of victim,by inoculation into brain or skin.some prion cases of CJD and GSS have shown inheritance pattern perhaps this is due to mutation in gene which changes amino acid pattern in a protein and  convert it into a prion.

By:Ashwani, bio- teacher, Phagwara.

Parathyroid

Thyroid

How do mosquitoes locate their victims?

1.Eyes:Mosquitoes use their eyes to locate their victims. research has shown that people wearing dark colour clothes like red, black, navy black etc are more likely to be easily located by the mosquitoes .
2. Blood type : people with blood group O  are to twice attractive to mosquitoes than those with Type A. most of people produce blood group specific secretions mosquito can detetect.
3. carbon dioxide : carbon dioxide is attractive to mosquitoes .they can sense carbon dioxide from a distance over 150 feet away.so more carbon dioxide one exhales,more attractive he/she is  to the mosquitoes .as we exhale carbon dioxide through nose therefore while sleeping or resting  there is more carbon dioxide around our head region.no surprise often  we hear  buzzing sound mosquito offer in our ears.
4. Body heat and sweat: Mosquitoes  can  also  detect  heat  of our body  and  sweat  also.  our sweat  contains  lactic acid, uric acid, ammonia  and some other compounds. the mosquitoes can sniff these compounds . So  sweaty peoples  are likely    to be more attractive  for the mosquito.  after strenous exercise  we  sweat more,  our body  emits more  heat . in such  state  we are more likely  to be attacked  by the mosquito.
5.Type of bacteria on skin .In one study,  humans were divided into those two groups. One group  that was  highly attractive to mosquitoes and other one with  those who were not.The attractive ones had more of certain microbes on their skin than the unattractive ones.
6.pregnancy:One study revealed that pregnant women are twice as attractive to Anopheles mosquitoes  as non-pregnant women.perhaps it was because women in late pregnancy exhaled 21 percent more volume of breath,hence more carbon dioxide  than non-pregnant women. Moreover, abdomens of pregnant women are about 1.25 fahrenheit  warmer than non pregnent women.
 7.beer.researchers found that significantly more mosquitoes come close to our body after drinking a 12-ounce beer.it was due to increased ethanol content in sweat and skin temperature after drinking beer)

Arthropoda

Arthropods are  cosmopolitan .They are found almost in every habitat. They are found in desert ,inside soil, in freshwater, in marine water, in snowy areas and also as parasites. Most of these are solitary or gregarious. some form colonies with social organisation.Body is divided into 3 regions head ,thorax and abdomen. In some species head is fused with thorax  to form cephalothorax .Segmentation is external. lnternal septa are absent. Symmetry is bilateral. Coelenterates are triploblastic animals with organ level of body organisation . Spaces in between organs merge and form blood filled cavity called haemocoel.Head is formed by fusion of 6 segments .it has various types of mouth parts. Eyes are compound . Exoskeleton is mostly made up of chitin. it undergoes moulting or ecdysis at intervals . Insects have wings made up of chitin. they have jointed legs and other appendages. Digestive canal is complete . Blood circulatory system is open type. Blood vessels cannot be differentiated into arteries and veins. Blood is colourless and is called hemolymph . Excretory system consists of green glands, malpighian tubules. gills, tracheae,book gills, book lungs, respiratory siphon are respiratory organs found in various arthropods. Nervous system consists of various  ganglia ,nerves and nerve plexus. Most arthropods are unisexual, few are hermaphrodites. fertilization can be external or internal. Parthenogenetic development of eggs into young ones is found in many arthropods like Honey Bee cockroach grasshopper etc. Asexual reproduction is absent. Development may be direct or indirect involving one or more larval stages. series of changes that convert larvae into adults are together called as metamorphosis.

Annelida

A characteristic feature of annelids is metameric segmentation i.e body shows external division by circular ring like annuli and corresponding internal division by septa. segments thus formed are called metamers. they are found in marine habitat, freshwater habitat and in moist soil also . symmetry is bilateral. body is triploblastic that is made up of 3 germ layers. they have organ level of body organisation. another characteristic feature is presence of setae in most of species. Setae are absent in leeches. some species have parapodia. which act as locomotor organ.annelids are coelomates . they have true coelom, which is schizocoel. in animal evolution annelids are the first to have coelom.The coelom contains coelomic fluid with certain types of cells. Coelomic fluid inside body cavity forms hydrostatic skeleton. in most of species respiration occurs by diffusion of gases throw skin. in some species respiration occurs through gills. digestive tract is complete, that is, have both mouth and anus. excretory system contains nephridia. blood circulatory system is closed type. blood is red due to plasma dissolved pigment erythrocruorin . true Blood vascular system is lacking. nervous system consists of mid ventral nerve cord with segmental ganglia and a nerve ring at interior end. sense organs are tactile receptors,photosreceptors, gustatoreceptors and also statocysts in some species. some species like earthworm, leech are hermaphrodite, whereas others like Neries are unisexual. development is direct in most of species, that is, no larval stage in life history. in some false like Neries larval stage (trochophore larva) is present.

Platyhelminthes

Platyhelminthes include flatworms. They  are bilaterally­ symmetrical. They are acoelomate i.e, lack a coelom .they ate triploblastic  ,that is, have three germ layers.most of species are parasitic.some are free living.they show cephalization of nervous system and  their nervous system consists of a head ganglion . Excretory system consists of specialized flame cells.  respiratory or circulatory systems are absent.exchange of gases occur  by diffudion through body surface.Non parasitic forms have  incomplete gut; even this is lack­ing in many parasitic forms.Movement in some  species occur  with help of body muscle. Others move along slime trails by the beating of epidermal cilia. Sense organs like ocelli (photoreceptors), chemoreceptors,statocysts ,rheoreceptors are present in some forms. Gut if present, is incomplete (without anus).tapeworms lack gut.The nervous system is ladder-like. It consists of the brain (head ganglion) and two main longitudinal nerve cords connected at intervals by transverse commissures.These animals are generally hermaphrodite but mostly cross fertilization occur. fertilization is internal. self fertilization occur in tapeworms.in some flat worms like Planaria asexual reproduction occur  by binary fission.Life cycle consists of one or more larval stages. In liver fluke (Fasciola hepatica)the larval stages are - miracidium, sporocyst, redia, cercaria and metacercaria . larval stages in tapeworm are onchosphere, hexacanth and cysticercus larvae. Flatworms show organ level  system of organisation.

Porifera

Porifera include the sponges . these are most primitive of multicellular animals.they are sessile and are fixed to some submerged object.The Plorifera belongs to Kingdom animalia. Most of members of this phylum are marine few are fresh water inhabitants. They maybe solitary or colonial. They have Cellular grade of body organisation shape is mostly cylindrical what are the shapes are also found. Body maybe radially symmetrical aur asymmetrical .They are diploblastic animals having two germ layers outer layer is called the derma and inner layer is called gastral layer.inbetween two layers there is  gelatinousmesogloea.it contains several amoeboid sales. Body has numerous pores called ostia for water entry and there is a large pore called osculum at the apex . coelom is absent but there maybe a cavity called spongocoel.water circulatory system is a unique features in the members of this phylum .endoskeleton consists of spicules which maybe calcareous made up of calcium carbonate  or silicious made up of silica. in some forms the Skeleton is made up of spongin fibres .spongin in a type of protein ingestion  is holozoic .digestion is intracellular .nervous system and circulatory system or absent. Both asexual and sexual reproduction occurs .asexual reproduction occurs by budding,gemmule formation and by regeneration .sexual reproduction involves fusion of gametes . fertilization is internal.Life cycle has free swimming larvae called amphiblastula or parenchymula.

Biology paper
class 10
 photosynthesis
MM30
1. name the followings.
A. green colour substance in plants.
B. structure containing thylakoids.
C. piles of thylakoids .
D.split of water molecules by light energy .
E.conversion of ADP into ATP.

2. select the most appropriate option. A.which one is not required for photosynthesis
a. carbon dioxide
b. oxygen
c. light
d.water
B.components of chlorophyll are
a. carbon
b.magnesium
c. nitrogen
d.all of these
C. glucose is synthesized in
a.light dependent phase
b. light independent phase
c. both of these phases
d. none of these
D. the main( primary) function of stomata is to
a. let the carbon dioxide enter
 Inside the leaf
b.to let oxygen released into the atmosphere
c.transpiration
d.all of these
E.which of the following is not an adaptation for photosynthesis
a. large surface area of leaves
b.transparent cuticle
c. numerous stomata
d. numerous chloroplasts on lower surface of leaves .
3.how will the following effect rate of photosynthesis
1.scarcity of water 2.rise in temperature 3.mineral deficiency
4.which is the location of the following structures mentioned in brackets
1.chlorophyll( thylakoids )
2.stomata( leaves )
5.explain why
1.chlorophyll appears green
2. grass grown in Shade turns yellow
6.term dark phase  is not appropriate for light independent phase
7. briefly explain
1.potassium ion concentration theory .
2.RuBP and Rubisco
8. given below is a diagrammatic representation of the internal structure of the organelle in plant cell study the same and answer the questions that follow
















1.identify the organelle.
 2.name the physiological process occurring in the organelle
3/. mention one way in which this processes beneficial to man.
4.name the phases of the process occurring in the part labelled as 1 and 2.
5. A chemical substance NADP plays an active part in one of the phases. Write the expanded form of NADP and state its role in above process.
6. Represent the physiological process mentioned in question 2 in the firm of chemical reaction.


7. The diagram below represent an experiment conducted to prove the importance of photosynthesis. study the same and answer the questions that follow.














1. name the factors being studied in the experiment .
2.why was the plant kept in a dark room before conducting the experiment
3.why was the experimental leaf then kept in a. boiling water b. methylated spirit
4. name the solution used to test for presence of starch in the leaf .
5.wat will we observe in the experimental leaf  at the end of the starch test .
6.give a balanced chemical equation to represent the process of photosynthesis.

Biology paper: Transpiration
MM 30.

A.name the followings
1. Openings on stem through which transpiration takes place .
2.a paper that turns pink when exposed to moisture
3.a plant in which stomata are sunken.
4..any two parts of leaf that allow transpiration.
5.A device used to Measure water intake by plant .

B.differentiate between the following on the basis of factors mentioned in the bracket
1.lenticel and stomata (opening and clothing)
2. transpiration and guttation (structure involved )
C.explain how
1. transpiration helps in bringing rain .
2.transpiration is a price paid for photosynthesis 3.transpiration helps to generate suction force .
D.how will the following factors influence the rate of photosynthesis?    1.decrease in atmospheric pressure 2.increase in humidity outside plant  3.increase in temperature
E.How are following structures useful to plant.
1. spines in cacti
2.shrunken stomata
F.given below is an apparatus used to study a particular phenomena in plants study the same and answer the questions that follows














1.Name the Apparatus
2.mention the limitations of this apparatus.
3. what is the function of the part marked reservoir .
4.which phenomena is studied with help of this apparatus.
5. What is the role of air bubble in the experiment?

G. Given below is an experimental set up to study a particular process.

• 
  

1. Name the process being studied.
2.Explain the process named in above question 1.
3.why is the pot covered with plastic sheet.
4.mention one way in which the process is beneficial to the plant.
5.suggest a suitable control for this experiment.

 Ashwani Kumar ,Biology teacher ,Patel Nagar,phagwara 9646388266