Flluid Mosaic Model of Plasma Membrane

It was well known that biomembranes can contract, expand,undergo fusion and can quickly repair  themselves. on the basis of these properties Singer and Nicolson (1972)proposed that

biomembranes are not solid but quassi fluid .according to this model the membranes do not have uniform arrangement of lipids and proteins but they are mosaic of two  There is a bilayer of phospholipid molecules proteins are present in between phospholipid molecules ,on the outer side of phospholipid bilayer and on the inner side of phospholipid bilayer. the proteins which are embedded in the phospholipid bilayer are called integral or intrinsic proteins. the proteins present on outer surface of phospholipid bilayer are called extrinsic proteins or peripheral proteins. The lipid bilayer is semi fluid .it allows the lateral movement of proteins .some proteins act as enzymes. some proteins help in active transport .some carbohydrate molecules may be attached to the phospholipid molecules forming glycolipids .the carbohydrates attached to proteins form glycoproteins 

Sciophytes

Sciophytes plants are also known as shade plants because they are adapted to low intensity of lights. stems are soft with large internodes. the  leaves are thinwith thin cuticle.stomata lie at level of surface of leaves and are resent on both the surfaces of leaves. root system his less extensive . they have low photosynthetic and metabolic rate.

Direct development vs Indirect development

Direct development vs indirect development

in case of direct development  the young ones resemble the adult in most of features except that they may be smaller in size, may have different color and are sexually immature.

On the other hand , in indirect development the young one do not resemble the adults in most of the features.

in case of direct development there is no larval stage whereas in case of indirect development there may be one or more larval stages.

in case of direct development the young ones have same ecological niche as that of parents whereas in case of indirect development young ones that is larvae have ecological nitch different  from that of parents .

in direct development  reorganization of internal and external structures occur during  transformation of young one to adults whereas in case of indirect development reorganization off internal and external   structures occur during  transformation of larvae to adults.

Ovipary, Vivipary and Ovovivipary

Ovipary,vivipary and ovovivipary

in ovipary the embryo develops inside the egg and eggs are laid before development of embryo. in other words the development of embryo occurs outside the body of female but inside the egg .after completion of embryonic development young ones hatch out of the egg.

Vivipary: the embryo develops inside body of female in her uterus. in the body of female the embryo is nourished through placenta .it occurs in eutherian and metatherian  mammals.

ovovivipary: egg is fertilized inside the body of female but it is not laid but returned within the reproductive tract of female until embryogenesis is complete. female gives birth to young one but young one develops in the egg within body of female and during development it is not nourished through placenta but it consumes food stored in the egg. examples sharks Rattle snake.

Characteristics of prokaryotic cell

1.Prokaryotic cells lack well organised nucleus 
2.the genetic material is present in the form of circular DNA .
3. DNA is not packed in chromosomes 4.the nuclear membrane is lacking 
5the DNA is not complexed with histones
6. different types of Pilli present 
7.mitochondria are lacking in prokaryotic cells 
8.chloroplast is absent. photosynthetic lamellae may be present in photosynthetic bacteria
9. membrane bound organelle  like endoplasmic reticulum, Golgi ,lysosomes are absent 10.the ribosomes are of 70s type 11.cytoplasmic streaming is not seen in the cells
12. the microtubules form cytoskeleton 
13.the cell wall consists of  mucopeptides which is known as 14.the flagella simple and do not have 9 + 2 pattern
Post by: ashwani kumar, biology teacher@ vigyan tutorials, phagwara.

Biology MCQs for NEET(UG)/AIPMT : Kingdom Monera

BY : ASHWANI KUMAR BIOLOGY TEACHER VIGYAN TUTORIALS PATELNAGAR PHAGWARA 9646388266 
 1.kingdom monera includes.
a.mycoplasma
b.bacteria
c.actinomycetes
d.all of these/
2.kingdom monera includes.
a.cyanobacteria
 b.mycelial bacteria
c.mycoplasma
 d.all of these/
3.kingdom monera includes
 a.amoeba
 b.paramecium
c.bacteria
d.none of these /
4.monerans are
a.unicellular
 b.mycelial
c.colonial
 d.all of these /
5.the organelles that are absent in monerans are
a.plastids
b.mitochondria
c.endoplasmic reticulum
d.all of these/
6.which of these organelles is not absent in monerans
a.ribosomes
 b.golgi
c.lysosomes
 d.plastids /
7.the genetic material in prokaryotes is
a. DNA
b.RNA
 c.can be a or b
d.proteins./
8.monerans are called procaryotes due to absence of
 a.distinct nucleus
 b.lysosomes
 c.golgi
 d.plastids
9.ribosomes in monera are
 a. 80S type
 b.70S type
 c.50S type
 d.60S type
Ans1.d 2 d 3.c 4.d 5.d 6.a 7.a 8.a 9.b
/By : Ashwani kumar.biology teacher, vigyan tutorials,new patel nagar phagwara 9646388266
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Biology MCQs for NEET(UG)/AIPMT : Kingdom Monera

BY : ASHWANI KUMAR BIOLOGY TEACHER VIGYAN TUTORIALS PATELNAGAR PHAGWARA 9646388266 
 10.1.Rhizobium 2Tolypothrix3Aulosira 4Azobacter/
the monerans that can fix atmospheric nitrogen are/
a. 12 
b.123 
c.134 
d.1234/
11.mycoplasma were discovered by 
a.Ricketts 
b.Leeuwenhoek 
c.Louis pasteur 
d.Nocard and Roux/
12. Mycoplasmal infection in human can be cured by 
a.Penicillin.
b.Tetracyclines 
c.both a and b 
d.none of these./
13. ATP synthesis is absent in 
a.viruses
 b. Rickettsiae 
 c. Chlamydiae 
d. All of these 
14. The Ricketssia Rochalimaea quintana causes 
 a.Q fever 
 b. Trench fever
 c. Endemic typhus 
 d. Epidemic typhus/
15. The common natural habitat of ricketssiae is 
a.cells of arthropod gut 
b.cells of liver 
c.brain cells.
d.lungs /
16.which of these are also called living fossils 
 a.PPLO 
b. Ricketssiae
 c. Archaebacteria 
d. Chlamydiae
17. Archaebacteria were discovered by
 a. Roux 
 b. Robert Koch
 c. Woese 
 d. Allen / 
Ans: 10 d.  11.d 12b. 13.d. 14b. 15a. 16.c 17c./
by: Ashwani kumar. Biology teacher vigyan. tutorials phagwara 9646388266