Classification
Phylum – Protozoa
- Simple, Acellular animals. (According to DOBELL).
Subphylum
– Sarcomastigophora
(Plasmodroma) - Locomotive organs are flagella or pseudopodia.
Class – Rhizopoda
(or sarcodina) - Locomotive organs are pseudopodia.
Order – Lobosa
(or Amoebina) - Pseudopodia are with rounded ends called lobopodia.
Genus – Amoeba.
Species
– Proteus - Body is variable in shape.
DISCOVERY AND HISTORY
R.V.
Rossenhoff has discovered Amoeba. Termed it as "Little Proteus" on
the name of a God of Yunan who was able to change his shape.
Saint
Vincent Named "Amiba" which was further changed to
"Amoeba".
Heirsch
Field has done detailed study of Amoeba.
- Most of
the species of Amoeba are found in fresh water and feeds on Algae and Bacteria.
- It is
present in dirty water with mud.
- Culture
of Amoeba can be done by Hay infusion process.
Dry
and clean leaves, grass, wheat grains are boiled in distilled water for 15
minutes.
After
filtration allow to stand for 2-3 days. Bacterial growth will take place.
Half
rotten leaves from pond are washed and put into filtrate. Within a week, filtrate will have good numbers of Amoeba.
- Two
species of Amoeba are also found in sea water or marine water.
-
Amoeba verucosa
-
Amoeba striata
- Amoeba
radiosa - Found in tropical areas. This is the most common species found in
India.
- Amoeba
proteus - Present in Temperate atmosphere. The maximum study is done of
this species because its structure is like a simple cell and the size is also sufficient.
-Amoeba
pelomyxa – (Chaos - chaos) – Giant Amoeba. This is the biggest Amoeba, its
structure is uncommon because it is exceptionally multinucleated.
SHAPE AND SIZE
Amoeba
is a micro organism. Size varies from .2 mm to .6 mm . It is colourless and
transparent. Shape is variable because pseudopodia are continously forming and
disappearing and also because pellicle is absent.
Exceptionally
due to presence of pellicle in Amoeba verucosa and striata,
pseudopodia are not formed and their shape is fixed.
Body of
Amoeba is differentiated into Protoplasmic membrane, Cytoplasm and Nucleus.
Protoplasmic membrane This is the outermost coating. It is 0.2m to 2m in thickness. It is a thin, soft,
selectively permeable unit membrane which is capable of regeneration.
Electron
microscope shows that hair like extensions are present on whole of the
membrane. These are called microvilli. They are mucoprotein in nature. These
micorvilli helps Amoeba in adhesion with ground.
CYTOPLASM
It is
divided into two parts
Outer – Ectoplasm or Ectosarc
Inner – Endoplasm or Endosarc
1. Ectoplasm
– It is transparent and present in form of a thin layer. It is devoid of
granules and structures. It is differentiated into two areas.
Outer
part is made of a watery fluid which is called "Hyaline layer". This
layer is thick in pseudopodia and called as "Hyaline cap". it gives
strength to pseudopodia. Internal part is made of plasmagel.
- The
ectoplasm of Amoeba proteus contains various perpendicular projections.
These are called as "longitudinal ridges". These ridges causes
friction and helps Amoeba to adhere with the ground.
2. Endoplasm
– It is semi transparent and granular.
All the structures of Amoeba are present in endoplasm.
According
to "Mast", Endoplasm is divided into two parts. Internal – Plama sol,
Peripheral – Plasma gel.
But
Electron microscope does not show this type of division. So whole of the
endoplasm is considered as Sol in nature as per the modern theory.
NUCLEUS
Normally
Amoeba is uninucleated but exceptionally Amoeba diploidia has two
nuclei. While Amoeba pelomyxa is multi nucleated.
The
nucleus of young or baby Amoeba is biconcave but biconvex in adult Amoeba.
A
network of protein fibers is present just inside the nuclear membrane. It is
honey comb in shape known as "Honey comb lattice". It maintains the
shape of nucleus.
Nucleus
of Amoeba is massive in nature, it means that chromatin material is more and nucleoplasm is less in quantity. Chromatin material is present in spherical
granules known as "Chromidia". These are 500-600 in number Every
chromidia is made up of one or two genes.
CELL ORGANELLS
CONTRACTILE
VACUOLE (C.V.) – It appears like a bubble of clear watery fluid enclosed
within delicate condensation membrane. Only one in number. It is formed by
union of many small vacuoles. C.V. is present in Endoplasm. Its position is not
fixed but usually it is present between nucleus and rear part of Amoeba
(Uroid).
Function
of CV is osmoregulation. The liquid medium around Amoeba is Hypotonic so water
enters in from outside continousely. This extra incoming water is thrown out by
C.V.
Functionally
C.V. is equivalent to kidney or nephron or uriniferous tubules of higher
animals.
Numerous
long tubules are related to C.V. These are called Feeding canals or Radiating
canals. These canals collect water from cytoplasm and drain into C.V.
Increase
in size of C.V. is due to filling of water called Diastole.
When
C.V. becomes sufficiently large it bursts near plasmalemma and water is thrown
out. This process is called systole.
Many
small vacuoles combines to form a C.V. The maximum energy is used in this
process so many Mitochondria surround the C.V.
- The
functional ability of C.V. increases when Amoeba is put in distilled water.
- When Amoeba
is transffered from fresh water to marine, C.V. disappears.
- When
marine amoeba is transffered to distilled water a new C.V. is formed.
Food
Vacuole – Many food vacuoles are present in endoplasm Every time when food
is ingested, a new food vacuole is formed and full digestion occurs in this
vacuole.
Functionally
it is closely related to alimentary canal of higher animals.
Water
Vacuoles - These are small, non contractile vacuoles filled with water
present in endoplasm. Its function is unknown.
Biurets
And Triurets - Many bipyramidal and tripyramidal crystals are present in endoplasm of Amoeba. These crystals are made up of excretory product carbonyl
diurea. Probably these crystals are excreted during reproduction.
- Stored
food of Amoeba is Glycogen and oil drops.
- Every
cell organelle like ER, Mitochondria, Golgi comples, Lysosomes, Ribosome etc
are present in cytoplasm except centriole.
- Endoplasmic
reticulum in Amoeba does not contain cisternae.
Locomotion in Amoeba
- Amoeba is a polypodial animal but
the locomotion is monopodial. Amoeba uses single pseudopodia in locomotion.
This movement is called amoboid movement.
- A
pseudopodium can form at any point on body surface. It first formed homogenous
fluid called hyaline cap. When this touches substratum, granular endoplasm rush
into it resulting elongation and become distinct pseudopodia.
- Speed is
.02 – .03 mm / min.
Locomotion in Amoeba is completed in three stages -
1. Adhesion
with base - In this process micrvoilli, longitudnal ridges and ions present in
water like Ca++, Mg++,
K+ etc. are
helpful.
2. Interconversion
of sol and Gel - This is essential for pseudopodia formation.
3. Contraction
in body - Amoeba moves forward by this contraction.
Theories Related with Locomotion -
1. Rolling
Movement theory - This theory was
proposed by "Jenings".
This
type of rolling movement was observed on Amoeba verucosa. This theory is
possible for only two species -
Amoeba
verucosa
Amoeba
striata
Amoeba
roll like a football during locomotion.
2.Contraction
theory This theory is given by Heitzman
& Schultze.
- According
to this theory a pseudopodium is formed due to contraction. Contraction occurs in posterior portion of Amoeba while pseudopodia forms in front part or in the
direction of locomotion.
This
theory is not valid because only contraction is not responsible for pseudopodia formation.
3. Walking
movement theory This theory was given
by Dellinger. This theory says that pseudopodia forms in the front part. These
pseudopodia serves as feet for Amoeba. With the help of these pseudopodia Amoeba
lifts up from the ground and feet like pseudopodia causes locomotion.
Pseudopodia disappeares in the back part and are appear as wrinkles. These
wrinkles are called Uroids. Due to these uroids, Amoeba shows polarity.
This
theory is not valid because at the time of locomotion Amoeba is in contact with
surface.
4. Surface
tension theory Proposed by Berthold.
Butschli and Rhumbler supported this theory. according to this theory
pseudopodia are formed due to difference in surface tension of body of Amoeba
and ground.
5. Fountain
Zone theory Proposed by Allen.
According
to this, sol is present in periphery while gel is inside. This central gel
moves like a fountain in the direction of locomotion. This fountain applies
pressure over ectoplasm and thus pseudopodia is formed.
But
this theory was discarded because in
Amoeba sol is always inside while gel is always outside.
6.Sol-Gel
theory is Based on change in viscosity
theory. Proposed by Hyman. Its detail study was done by Pantin and Mast
This
theory suggest that pseudopodia are formed due to interconversion of sol and
gel.
In
locomotion sol flows in the direction of locomotion and breaks the gel barrier.
This sol strikes with the ectoplasm. After striking it moves on either side and
converts into gel.
In
locomotion the gelation process occurs in front while solation (gel - sol)
occur in rear.
- Sol
continousley strikes with ectoplasm therefore ectoplasm grows in size and
spreads
outward hence a small hyaline cap as a small bulge representing
begining of pseudopodia. This process helps in pseudopodia formation.
- Pseudopodia
is a tube like structure of ectoplasm in which endoplasm is filled. The wall of
pseudopodia is made up of gel while sol in inside.
Drawbacks
1. This theory do not explain the
sol-gel interconversion.
2. It does not mention about the force by
which sol moves forward.
Some
theories in favour of sol-gel theory :
(i) Molecular
folding unfolding theory – Proposed by Goldacre
and Lorch. It explains the sol-gel interconversion. This is a Biochemical and
biophysical process. The sol form of protoplasm is due to tertiory structure
(folded state) of protein.
While
the gel form is due to secondary structure (Unfolded state) of Protein.
(ii) Contraction
Hydraulic theory
Earliar
given by Schultze and detailed explanation was give by Rinaldi. It explains how
sol moves in the direction of locomotion. According to this, actin and myosin
type of proteins are present in rear portion of Amoeba. These proteins produce
hydraulic pressure by contraction. This pressure is maximum in front, minimum
in middle and medium in rear.
According
to "Huxley" the proteins participating in solution and gelation are
similar to actin and myosin of muscles fibres.
Nutrition
Nutrition
in Amoeba is Holozoic or Zootropic which involve ingestion of food and then
digestion and absorption.
Amoeba
is omnivorous. It likes to take bacteria, algae, cilliated and flagellated
Protozoans. There is no pore for ingestion and excretion of digested food. Any
part of plasmalemma can ingest food and excrete digested food.
Some
protozoans like Paramoecium contain pore. These are called Cytostome and
Cytoproct. (or cytopyge)
Methods of food ingestion (Studied by Rhumbler)
1. Import -
Amoeba do not effort in this method. Any moving food when strikes with amoeba
it is embeded into the cytoplasm (Passive food ingestion).
2. Invagination
- By this process small and non-motile food is ingested. This type of food
comes in contact with plasmalemma which invaginates and food is ingested due to
invagination of plasmalemma in the form of a food vacuole.
3. Circumfluence
- This process is used to ingest large and nonmotile or less active food e.g.
Filaments of algae.
In this
process cytoplasm of amoeba flows around the food and encircle it.Plasmalemma
invaginates and forms a food cup which further converts to a big food vacuole.
4. Circumvallation
- By this process amoeba ingests active, motile food. Food is surrounded by
several small pseudopodia. Later these pseudopodia unites and forms a food cup.
Finally prey is embedded in the endoplasm. Amoeba can also ingest colloids from
surrounding by pinacytosis and form pinocytic vesicle.
Digestion
Digestion
takes place in food vacuoles by means of lysosomal enzymes release from
Lysosome which get fuse and merge with food vacuoles. These enzyme work
effectively only when medium in food vacuole is alkaline.
- Just
like higher animals digestion is completed first acidic and then alkaline
phase.
- First
HCl produced from fluid of vacuole made food loose, soft and semitransparent.
And
simultaneously vacuole loses water and become smaller. Then Lysosome
release their enzyme into vacuole which made vacuole alkaline.
- Proteolytic
enzymes like trypsin, peptidases and lipolytic enzyme lipase are found but
carbohydrate-digesting enzyme or amylolytic enzyme is very less.
- Thus
proteins hydrolysed to amino acids and fats to fatty acid and glycerol. Due to
increase osmotic concentration water is reabsorbed.
- Food
vacuole remain in endoplasm for about 30mts for completing digestion. End
product of digestion diffuse out from the vacuole to all part of body.
- Excess
amino acid changed to sugar and store as glycogen as reserve food.
- Food
vacuole with undigested food is thrown out.
Respiration And
Excretion
Both
these functions are completed by plasmalemma through diffusion.
Amoeba
is an obligate aerobe. It depends only on aerobic respiration. So when Amoeba
is put under O2 less water it dies.
- In view
of excretion Amoeba is Ammonotelic.
Reproduction
1.Binary
fission - Simplest type of reproduction. It occurs in desirable condition. In
this process divison is primitive type of mitosis called as Cryptomitosis.
Phases
of this division are as under -
i.
Prophase - Contractions in C.V. Stops. Numerous small pseudopodia arises on
whole of the surface of Amoeba. Amoeba is covered by hyaline caps. Therefore
entry of water becomes slow.
Nucleolous
and Honey comb lattice in nucleus disappears but nuclear membrane persists.
Nucleolous
and Honey comb lattice in nucleus disappears but nuclear membrane persists.
Chromidia
become condensed and clear. Spindle formation starts in nucleus. These are called intranuclear spindles.
ii.
Metaphase - Chromidia forms metaphase plate by adjusting themselves in the
middle of nuclues.
Spindles
are arranged on different poles of nucleus. These are called multipolar spindle. This is an unique character of binary fission in Amoeba.
iii.
Anaphase - Pseudopodia becomes less in number but size increases. Multipolar
spindles are converted into bipolar spindles (spindle fibers). Now chromidia separate so that chromidia approaches the
two poles of nucleus. Simultaneously nucleus becomes larges and show
constriction in middle.
At the
end of Anaphase nucleus is dumble shaped.
iv.
Telophase - At this stage nucleus and cytoplasm divides. It results in
formation of two daughter Amoeba. Size of daughter Amoeba is greater than the
half of the size of parent Amoeba.
Old
C.V. remains in any one of the daughter Amoeba. While the other forms a new
one. Binary fission is completed in 30 mt. It maybe repeated after 48 hrs.
2. Sporulation
-
i.
Sometimes Amoeba reproduces by sporulation in unfavourable conditions.
ii.
When excessive energy is spent continously, binary fission ability decreases.
To reproduce further it does
sporulation. Spore is the resting stage of Amoeba hence it saves energy.
- In
sporulation Amoeba retracts its pseudopodia and becomes sphere shaped.
- Nuclear
membrane disappears and chromidia disperse in the sets of 2 or 3 chromidia.
Every set of chromidia is surrounded by a newly formed nuclear membrane.
- After
that cytoplasm divides and breaks in 200 pieces and surrounds each small
nucelus. Every piece now secretes a hard and thick coat around itself. This
structure is called spore.
- About
200 spores are formed by this process. Coat of spore is made up of chitin.
- Now
plasmalemma of parent Amoeba dissolves and spores are spread out.
- When
favourable conditions arrive, spore germinates. They absorb water and swollow.
Thick coat splits and a young Amoeba comes out.
- In this
young stage endomitosis occurs in nucleus so that chromidia increases in number
up to 500-600. Nucleus formed by endo mitosis is called Restitution or polyenergid
nucleus.
- Spore
also helps in dispersion of Amoeba.
3.Encystment
and Multiple fission This process is
used under unfavourable conditions, like lack of O2 , lack of food and at high temp. In this case
Amoeba secretes a three layered thick coat around itself called cyst. Coat of
cyst is made up of chitin like that of spore. It is impermeable to water and
permeable to O2 and CO2.
Inside
cyst amitosis occurs several times so that 500 small Amoeba are formed. These
are called pseudopodiospores or Swarm spores.
- On
return of favourable conditions cyst spits and Amoeba get freed in water.
- According
to modern scientists, multiple fission is very rare.It is not a process of
reproduction it is a process of perennation.
- Amoeba
is least active inside cyst. This phenomenon is called "Suspended Animation". This is also
a process of dispersion but its efficiency is more than spore.
Rejuvenation - This is also called non-functional
conjugation. In this process two old amoeba come close to each other and adhere
themselves. After a while they get separated.
Now these both amoeba are more active than before. (No Exchange of
matter.)
Regeneration
- Studied by Bruno & Hoger. Amoeba has tremendous power of regeneration.
- Any part
of Amoeba which contain at least one
chromidia may regenerate but piece without nuclears can not regenerate.
Immortality in
Amoeba Studied by Hertman
Amoeba
is immortal because its natural death do not occour as a parent Amoeba is
converted completely into two daughter Amoeba by binary fission.
Immortality
can also be explained on the basis of "Germplasm theory of weisman".
According to this theory Amoeba is not differentiated into somatoplasm and
Germplasm.
This
type of differentiation is present in multicellular animals.
Irritability
-Amoeba
has protoplasmic grade of irritability.
- Maximum
taxis movement of Amoeba are negative, these are called phobotaxis.
- Some
positive taxis are also present these are called philotaxis.
Types of irritability :
1. Thigmotaxis
- Normally phobotaxis, but in response to food it is always philotaxis.
2.Phototaxis
- Amoeba likes dim light. So phobotaxis is seen in response to bright light
& darkness.
3.Thermotaxis
- Optimum temp is 20-250C. When Amoeba is
kept suddenly under high temperature it dies but when rise in temp is gradual
it forms cyst.
4.Chemotaxis
– Amoeba shows phobotaxis when kept under water in which those chemicals are
present that are not present normally in water.
5. Galvanotaxis
- When low current is passed Amoeba moves toward cathode but in high current it dies.
6.Rheotaxis
- Amoeba moves with the flow of water.
7. Geotaxis- Philotaxis because Amoeba like to live in
bottom. These animals are called benthos or benthic.
ENTAMOEBA HISTOLYTICA
Entamoeba
histolytica is discovered by Lamble. Losch discovered its pathogenic
nature.
Entamoeba
Histolytica is a parasitic Amoeba and it causes "Amoebic dysentry".
A patient with this disease has acidic stools. Stool also contain mucous, blood
and cyst of Entamoeba. So this disease is diagnosed by stool test.
Entamoeba
Histolytica is a parasite of large intestine(colon) of man. It secretes histolytic
enzymes which causes harm to wall of intestine. Entamoeba destroys the mucosa
and submucosa of colon and enters in its wall and injest tissue, RBC etc, and
form flask shaped ulcer from which mucous and blood comes out and pass into
stools of the host. It may also approach in other organs of body like liver,
lungs, kidney, brain etc. through blood circulation.
Basically
structure of Entamoeba is similar to Amoeba, but C.V. is absent in Entamoeba.
It's
food vacuole contains R.B.C., W.B.C. and bacteria as these substance are used
as food.
Nucleus
of Entamoeba is vesicular i.e. chromatin material is less and Nucleoplasm is
more.
Chromidia
are arranged on periphery of nucleus. At the center of nucleus a false
nucleolus or karyosome or Endosomes occurs. Endosome is surrounded by a
small clear shiny and transparent area
which is called Halo. Nucleoplasmic striations connect Halo to chromidia.
Entamoeba
Histolytica is monopodial animal. In its rear portion plasmalemma is
geletinous and sticky. It helps in sticking of food particles. Food is ingested
by the process of invagination. This is the only process of taking food.
Two forms of Entamoeba are there :
(i) Trophozoites or Magna form.(20-30u)
(ii) Precyst or Minuta form.(12-15u)
Trophozoites
form is larger than Minuta form. Trophozoites is the adult stage of Entamoeba.
This stage of Entamoeba is motile, actively feeding and pathogenic.
Life
Cycle - Few daughter Amoeba which are formed by the asexual multiplication of
Trophozoites grow in to normal adult whereas few dauthter Amoeba remain small
and escape from the lumen of the colon known as minuta form or precystic
Amoeba.
Cytoplasm of these minuta contain only one or two granules
of glycogen, but contains a dense body called as "Chromatoid body".
Possibly it is made up of Ribo nucleoproteins which further disappear.
Minuta
secretes a thin but strong coat around itself called cyst. Nucleus of cyst
undergo two mitosis and a tetra nucleated cyst is formed. It is carried out
from the body by stools of the patient.
This tetra
nucleated cyst is the infective stage of Entamoeba for human.
Cyst
enters in human by impure water and food. Houseflies also carry these cyst to
food. When these cysts reach to colon, their hard coat is damaged. This process
is called hatching or excystment. Now
Tetra nucleated stage comes out. This is called Metacyst. Metacyst undergo
binary fission and eight Entamoeba are formed.
All
these Entamoeba enters the wall of colon and after growth converted into
Trophozoite. Some medicines used in prevention of diseases caused by Entamoeba
Histolytica are Emetine, Diodoquin, Dependal, Carborsone metrogyl, Magma,
Amicline.
ENTAMOEBA
GINGIVALIS
Size of
trophozoite - 12-20u.
It is
present in Tartar which is deposited in between teeth. Approximately 70% humans
are infected by this. Some times it also infect gums. It has 2-3 pseudopodia
and contain several food vacuole.
Entamoeba
gingivalis is a human parasite but it is not pathogenic.It helps some
pathogenic protozoa in infection e.g. Trichomonas tinax, Trichomonas
buccalis both of these causes pyorrhoea.
- Entamoeba
gingivalis does not form cyst.
- It
spreads through mouth to mouth by kiss. It trophozoites feeds on bacteria,
debris WBC.
- Prevention
may be done by using sensoform mouth wash
- Treatment
can be done by Garamycin.
ENTAMOEBA COLI. (E. Coli) - (Trophozoite - 20-40 m )
- This
species is found in human colon.
- It shows
commenselism Host is neither in gain nor in loss.
- It feeds
on non digestive food & Bacteria and do not invade colon wall.
- Eight-nuclei
are found in the mature cyst.
Special Point
1. Pelomyxa
is the biggest Amoeba.
2. Amoeba
proteus is a free living and solitary animal
3. Amoeba
is omnivorous.
4. Amoeba
is polypodial where as Entamoeba is Monoipodial
5. Amoeba
shows polarity as uroids are present on back.
6. Chromatin
material of Amoeba is granular and called chromidia.
7. Gaseous
exchange in Amoeba is done through body surface.
8. Excretion
of Ammonia is also done through body surface.
9. The
universal theory for locomotion in Amoeba is sol-gel theory
10. Mechanism
of binary fission in Amoeba is cryptomitosis.
11. General
method of reproduction in Amoeba is binary fission.
Problems for practice
Problems for practice
1. What is absent in Amoeba-
(1) Mitochondria (2) Ribosome
(3) Golgibody (4) Centriole
2. Attachment
of Amoeba to substratun is facilitated by -
(1) Rough surface
(2) Secreting chemicals
(3) traces of inorganic ions
inwater (Ca++, Mg+2, K+)
(4) low surface tension
3. The excretion in Entamoeba
histolytica takes place by -
(1) Contractile vacuole
(2) General body surface
(3) Food vacuoles
(4) none of the above
4. Amoebic dysentry or
amoebiasis is caused by -
(1) Entamoeba histolytica
(2) Amoeba proteus
(3) Entamoeba coli
(4) Entamoeba indica
5. Excretory product in Amoeba
is -
(1) Ammonia (NH3) (2) Urea
(3) Uric acid (4) none
6. If an Amoeba
is place in oxygen less atmosphere it -
(1) Dies immediately
(2) form pseudopodia
(3) Form cyst
(4) rapidly multiplies
7. If nucleus is removed
from Amoeba-
(1) Dies immediatedly
(2) Remaince alive
(3) froms pseudopodia
(4) does not grow and dies
ultimately
8. Entamoeba
histolytica differs from Amoeba proteus due to absence
of
(1) Nucleus
(2) Food vacuole
(3) contractile vacuole
(4)
all of the above
9. In Amoeba,
lobopodia are formed due to
(1) Excess of ATP
(2) Sol-gel interconversion
(3) entry of more water in body
(4) spontaneous
10. If Amoeba
is placed under unfavourable conditions
(1) retracts pseudopodia
(2) forms pseudopodia
(3) undergoes rapid division
(4) remains alive
11. How many Amoeba
are formed from a single cyst of Entamoeba histolytica
(1) 2
(2) 4
(3) 8
(4) 16
12. Food is stored in which
form in Entamoeba histolytica
(1) Glycogen (2) Fats
(3) Protein (4) Starch
13. Entamoeba gingivalis
found in
(1) Last end of tongue
(2) In between gums and teeth
(3) Inner surface of
cheeks
(4) Throat
14. Amoeba
exhibits tactic movement in response to
(1) Touch (2) Heat
(3) light (4) all of the above
15. In Amoeba
amount of water increases by
(1) by endoosmosis
(2) at the time of ingestion of
food
(3) by matabolism reactions
(4) all of the above
16. Entamoeba coli
obtain nutrition from
(1) Saliva
(2) Mucous
(3) Tissue layer
(4) Undigested food in intestine
17. If a marine Amoeba
is transferred to fresh water
(1) Die
(2) No change
(3) Form New contractile vacoule
(4) It bursts
18. Which substance is
minimum in Amoeba body
(1) Carbohydrates (2) Protein
(3) Fats (4) Nucleic Acid
19. Naked Amoeba
found in
(1) Fresh water (2) Marine water
(3) Wet soil (4) All of the above
20. During digestion changes
in food vacuole of Amoeba occur in
(1) Only PH (2) Only size
(3) PH and size (4) None
21. The pseudopodia are
formed in Amoeba
(1) When it comes in contact with
food particles
(2) By sol-gel transformation
(3) When body stricks with
substration
(4) When food is large
22. In which class Amoeba
is placed
(1) Ciliata (2) Mastigophora
(3) Sporozoa (4) Sarcodina
23. By which method active
food like Paramoecium ingested by Amoeba proteus-
(1) Circumvallation (2) Circumfluence
(3) Invagination (4) Import
24. Contractile vacuole found
in
(1) Amoeba proteus
and Entamoeba
(2) Plasmodium and Amoeba
Proteus
(3) Paramoecium and Amoeba
Proteus
(4) Euglena and Entamoeba
25. Which type of pseudopodia
are present in Amoeba Proteus
(1) Lobopodia (2) Exopodia
(3) Filopodia (4) Reticullopodia
26. Asexual reproduction in Amoeba
(1) Binary fission (2) Multiple fission
(3) Sporulation (4) all of the above
27. In which type of medium
occours in food vacuole of Amoeba
(1) First acidic and then alkaline
(2) only alkaline
(3) first alkaline and then acidic
(4) only acidic
28. By which method solid
food is ingested in Amoeba
(1) Phagocytosis (2) Pincocytosis
(3) both (4) none
29. Which cell organelle is
most abundant around food vacuole in Amoeba
(1) Golgibody (2) Lysosome
(3) Ribosomes (4) Mitochondria
30. Circumfluence in Amoeba
is a method of
(1) Binary fission (2) locomotion method
(3) Foot ingestion (4) Excretion
31. Amoeba
exhibits positive response to
(1) Strong light
(2) dim light
(3) strong electric current
(4) strong chemical substances
32. Besides locomotion
pseudopodia of Amoeba help in
(1) Reproduction (2) Ingestion
(3) Respiration (4) Excretion
33. Site of solation in Amoeba
is
(1) Anterior end where pseudopodia
form degenerate
(2) Posterior end where pseudopodia
degenerate
(3) Places where C.V. disappear
(4) Posterior end where pseudopodia
form
34. Main function of
contractile vacuole in Amoeba
(1) Excretion of excess of salts
(2) Excretion
(3) Temperature regulation
(4) Osmoregulation
35. In weak electric current Amoeba
(1) Movement towards Cathode
(2) Movement towards Anode
(3) Dies
(4) Encystment
36. In which form Amoeba
ingest food
(1) Ingestion of whole animal
(2) Fully digested food
(3) Animal of class crustacea
(4) none of the above
37. A fresh water Amoeba
respires by means of
(1) Gills
(2) Food Vacuole
(3) Plasmalemma
(4) Contractile vacuole
38. In Amoeba
nitrogenous wastes are expelled out through
(1) Pseudopodia (2) Hyalinecap
(3) Plasmalemma (4) Contractile vacuole
39. The method of food intake
in Amoeba is called
(1) Saprophytic (2) Holozoic
(3) Holophytic (4) Parasitic
40. A full grown Amoeba
undergoes binary fission, the total surface area of one
daughter Amoeba
soon after division is
(1) Equal to half parent Amoeba
(2) Slightly less than half of
parent Amoeba
(3) Same as parent Amoeba
(4) slightly more than half of
parent Amoeba
41. Amoeba
reproduces during unfavourable conditions by-
(1) Conjugation (2) Binary fission]
(3) Encystment (4) All of them
42. When the pond is going to
dry Amoeba will
(1) Show no change
(2) Feeds quickly
(3) Encysts
(4) Divides by binary fission
43. The conversion of
plasmagel into plasmasol and vice versa in Amoeba was first
studied by
(1) Pantin (2) Hymen
(3) Mast (4) Taylor
44. Binary fission in Amoeba
occurs
(1) When environment is favourable
(2) Food is abundant
(2) Food is abundant
(3) Temperature is suitable
(4) Food abundant and temperature
is suitable
45. Contractile vacuole of Amoeba
is analogous to vertebrate
(1) Uriniferous tubules (2) Pulsating heart
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