Difference between Catkin and Spadix inflorescence

Catkin inflorescence is pendulous i.e, hanging whereas spadix inflorescence is mostly upright.

Catkin Inflorescence is not covered by spathe whereas spadix inflorescence is covered by spathe.

In catkin inflorescence male and female flowers are present on different catkins whereas in spadix inflorescence male and female flowers may be present on same spadix or on different spadices.

In catkin inflorescence whole peduncle is fertile whereas in spadix inflorescence apical part of peduncle is sterile i.e flowerless and is called appendix.

In catkin inflorescence there is nothing special to attract the pollinators whereas in spadix inflorescence spathe and appendix are coloured which attract the pollinators.

Catkin : example, Morus alba,
Spadix: example, Colocasia

By : Ashwani Kumar,
biology teacher,
Phagwara.

Difference between spike and spadix inflorescence

A spike inflorescence is that in which elongated peduncle bears sessile flowers in acropetal order. A spadix is a modified form of spike in which fleshy peduncle bears sessile flowers.

In spike whole peduncle bears flowers whereas in spadix upper sterile part of peduncle is called appendix whereas lower sterile part bears unisexual flowers .

In spike, inflorescence  is not covered by spathe whereas in spadix inflorescence whole inflorescence is covered with one or more large bracts called spathes.

By: Ashwani, biology teacher, Phagwara.

Difference between Corymb inflorescence and umbel inflorescence

1.  In case of corymb inflorescence peduncle is long and bears flowers at different levels. In case of umbel inflorescence peduncle is reduced to a point and all flowers arise from this point .

2. In corymb inflorescence flowers are present in a acropetal order whereas in umbel inflorescence flowers are present in centripetal order.
3. In corymb Inflorescence older flowers have longer pedicels whereas in umbel inflorescence there is no much difference in length of pedicels.
4. In corymb inflorescence involcure is absent whereas in umbel inflorescence involcure is mostly present.

By: Ashwani, biology teacher,Phagwara.

Difference between pedicel and peduncle.

Stalk of the flower bearing a flower is called pedicel whereas flower bearing axis of shoot is called peduncle and it may have one to many flowers.

By: Ashwani, Biology teacher,Phagwara.

Difference between phylloclade and phyllode

1. Phylloclade is a modified stem which is green and performs photosynthesis.on the other hand, a phyllode or phyllodia is modified petiole with or without rachis which performs photosynthesis.

2. Phylloclade arises from axil of leaf .Phyllode is not an axillary structure as it itself is a modification of a part of leaf.

3. Axillary bud is absent as phyllode itself develops from a axillary bud. In case of phyllode axillary bud is present .

4. Phylloclade bears leaves , flowers and fruits whereas these structures are absent in phyllode.

5. Phylloclades are mostly succulent and store water, latex, food etc .Phyllodes are never succulent.

6. Phylloclade may help in vegetative reproduction whereas a phyllode do not help in vegetative reproduction.

By: Ashwani, biology teacher,Phagwara.

Difference between leaf tendril and stem tendril

1. Leaf tendrils are mostly unbranched whereas stem tendrils may be branched or unbranched .

2. In case of leaf tendrils scale leaves are absent whereas in case of stem tendrils scale leaves may be present at the point of branching.

3. Buds are absent in leaf tendrils whereas axillary buds may be present in the axil of scale leaves.

4. In case of leaf tendril whole leaf or a part of it develops into tendril whereas a branch of stem or a bud develops into stem tendril.
By: Ashwani Kumar,
Biology teacher,
phagwara.

Pinnate Compound Vs Palmate Compound Leaf

In pinnate compound leaf the leaflets are present on either side of long axis whereas in palmately compound leaf the leaflets are attached to common axis.

In pinnately compound leaf there are two rows of leaflets whereas in palmately compound leaf there is a cluster of leaflets.

In pinnately compound laf there is no joint between leaflet and axis whereas in palmately compound leaf there is joint between leaflets and point of attachment.

Leaflet bearing axis is continuation of petiole or a branch of midrib whereas in palmately compound leaf the leaflets are attached to the tip of the petiole.

By: Ashwani,Biology teacher, Phagwara.

Simple leaf Vs Compound leaf

In simple leaf lamina is not divided into lobes or leaflets whereas in compound leaf lamina is divided into distinct leaflets.

Simple leaves develop on stem in acropetal order whereas in compound leaf all the leaflets develop simultaneously therefore, there is no acropetal arrangement.

Simple leaf may have bud in it
s axil whereas in compound leaf a bud is present in axil of whole leaf but individual leaflet does not bear buds.

In simple leaf stipule may be present at base whereas in compound leaf stipule may be present at base of whole leaf but not at base of individual leaflet (exception is Beans).

By:Ashwani, Biology teacher,Phagwara.

Reticulate Vs Parallel Venation

1. In reticulate venation the main vein give rise to lateral veins which divide and redivide to form a network or reticulum. On the other hand in parallel venation the veins run parallel to each other and do not form reticulum or network.

2. Reticulate venation is found in dicots whereas parallel venation is found in monocots.

By: Ashwani Kumar,
Biology teacher,
Phagwara

Prop roots Vs Stilt roots

1.Prop roots develop from the upper horizontal branches of the tree whereas stilt roots develop from the basal node of the plant stem.

2. Prop roots grow vertically whereas the stilt roots grow obliquely from the basal node.

3. Prop roots give support like a pillar whereas stilt roots work like ropes of a tent.

4. Young prop roots are hygroscopic whereas young stilt roots are not hygroscopic.

Prop roots are found in banyan whereas stilt roots are found in maize and sugarcane.

By: Ashwani Kumar,
biology teacher ,Phagwara

Difference between Tap root system and Adventitious root system

1.Tap root system arises from radicle of the embryo whereas the adventitious roots arise from any part of the plant body other than radical or its branches .They can arise from stem, leaves etc.

2.In tap root system there is single main root called tap root which bears branches in an acropetal manner .In adventitious roots there are number of equally strong fibrous roots present in clusters.

3.Tap root system is underground whereas adventitious roots may be underground or aerial.

4.In tap root system the primary root or tap root  persists throughout life of plant. In adventitious root system the primary root is short lived and is replaced by adventitious roots.

5.Tap root system may be deep feeder or surface feeder whereas adventitious root system is mostly surface feeder.

By: Ashwani Kumar,

Biology teacher,Phagwara

Difference between Respiratory roots and Assimilatory roots roots

1. Respiratory roots occur in plants growing in marshy areas whereas assimilatory roots occurs in plants growing in terrestrial and aquatic habitat and even in epiphytic plants.

2. Respiratory roots are non green
hence do not perform photosynthesis. Assimilatory roots are green and perform photosynthesis.

3. Respiratory roots are negatively geotropic . Assimilatory roots are diageotropic ,which means they tend to grow horizontal to the line of gravity .They may be plagio-geotropic which means they tend to grow at an angle oblique angle to the line of gravity.

4. Respiratory roots have covering of cork whereas assimilatory roots lack the covering of cork.

5.Respiratory roots have lenticels for gaseous exchange. Assimilatory roots lack lenticels. The gaseous exchange occurs through the general surface of roots.

6. Respiratory roots are modifications of tap root system whereas assimilatory roots are a type of adventitious roots.

By: Ashwani Kumar,
Biology teacher,Phagwara .

Differences between Gymnosperms and Angiosperms

1.The gymnosperms usually are not herbaceous, whereas, majority of angiosperms are herbaceous.

2. The gymnosperms are perennial whereas angiosperms may be annual biennial or perennial.

3. In gymnosperms the reproductive structures are cones which are unisexual, whereas, in angiosperms the reproductive structures are flowers which may be unisexual or bisexual.

4. In gymnosperms, during pollination the pollen grains fall on the micropyle , whereas in angiosperms they fall on the stigma.

5. In gymnosperms the pollination is  mainly occurs through anemophily whereas in angiosperms the pollination may occur through anemophily, entomophily ,hydrophily also .

6.Ovules are naked in gymnosperms ,whereas, they are protected in ovaries or carpels in angiosperms.

7. in gymnosperms the archegonia are present in female gametophyte, whereas, angiosperms lack archegonia.

8. In gymnosperms there is no double fertilization, only single fertilization occurs ,whereas, in angiosperms double fertilization occur.

9.Cleavage polyembryony is common in gymnosperms where is it is absent in angiosperms.

10. In gymnosperms zygote undergoes free nuclear division where is zygote of angiosperms does not divide by free nuclear division .

11.Vegetative reproduction is rare in gymnosperms, whereas, it is very common in angiosperms.

Dinoflagellates and Red Tides

Dinoflagellates are unicellular, eukaryotic organisms.most of the species are marine.some are found in freshwater.size ranges from 15 to 40microns.A species Noctiluca is larger ,can have size around 2mm.they have two flagella which help them to swim.their chromosomes are in highly condensed form.they have large quantity of DNA.although they are eukaryotes but they don't have histones.many dinoflagellates are photosynthetic.all are not photosynthetic.some dinoflagellates are symbiotic and live in marine invertebrates like sponges,corals,jellyfish etc some live within ciliates,foraminiferans and radiolarians.the non photosynthetic species are heterotrophic.they feed on other planktond or even on each other .noctiluca can even feed on fish eggs.several species of dinoflageyshow bioluminescence. dinoflagellates are second producers after diatoms in aquatic ecosystem. many genera of dinoflagellates cause red tide.these include Gonyaulax, Karenia ,Gymnodinium ,Dinophysis, Noctiluca, Chattonella,Amoebophyra.these contain photosynthetic pigments whose colour varies from brown to red. some red tides are bioluminescent.in addition to dinoflagellates red tides also contain diatoms.some red tides are harmful .some species of dinoflagellates causing red tides produce toxins which cause death of fishes. human can get affected by eating shell fish caught from water having red tide recently. shell fish feeds on dinoflagellates and eating toxic dinoflagellates in large amount during red tide cause accumulation of toxin inshell fish.eating such fish can cause serious health problems to man.

By: Ashwani,Biology Teacher,Phagwara.

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.