Paramecium

Question 1

Locomotion in Paramecium

Answer 1

• Paramecium performs locomotion by two method
• They ere;
1. Creeping Locomotion
• It occurs with the help of pellicle and cilia
• It simply glide along using cilia of its oral surface
• The body of Paramecium is elastic, so it can easily bends or squeeze
through small passage narrower than body
• This type of locomotion is performed at the time when there is many
obstacles on water surfaces

2. Ciliary Locomotion
   • It is main method of locomotion, occurs through cilia
   • The cilia can beat forward or backward enabling the animal to swim
   anteriorly or posteriorly
   • If the animal wants to move forward, the cilia stiffen and bend
   backward rapidly to touch almost the body surface (called effective
   stroke)
   • Then the cilia become limp and return slowly to the original
   position(recovery stroke)

Question 2

Nutrition in Paramecium

Answer 2

• Holozoic nutrition
• Food comprise minute living organism mainly bacteria, unicellular
algae, diatoms, yeast etc.
• It feeds during rest or slowly moving period
• The beating of cilia of oral groove cause food laden water to be swept
into the oral groove
• food then pass to vestibule from where it enters into the endoplasm
through cytostome and cytopharynx and settle down in the reservoir,
forming food vacuole

Question 3

Digestion

Answer 3

• It is intracellular; inside the food vacuole with the help of certain
enzyme secreted by protoplasm into the vacuole
• The contain of food vacuole is first acidic (PH about 4) and then
alkaline
• When food vacuole become full of food, it is leaved in endoplasm and
digested food is distributed by cyclosis process
• Undigested food expelled out by cytopye

Question 4

Respiration in Paramecium

Answer 4

• It occurs by general body surface by the process of diffusion
• Body pellicle is semi-permeable through which exchange of gases
takes place

Question 5

Excretion in Paramecium

Answer 5

• It occurs through general body surface
• It also occurs through cytopyge

Question 6

Asexual reproduction in Paramecium

Answer 6

Paramecium reproduce asexually during favorable condition by
transverse binary fission
• It completes in following steps;
- Paramecia stops feeding and oral groove disappears. Each daughter
paramecium develops its own oral groove
- Macronucleus change its shape, become elongated and divided
amitotically into two
- Micronucleus also change its shape, become spindle and divide
mitotically into two.
• The endoplasm is divided into two transversely in the middle of the
body. So that one contractile vacuole goes to one half and another to
another half
• The daughter paramecium formed from anterior half is called proter
while posterior half is called opisthe
• The fission complete within 20 minute and in 24 hours it divides 2 or
3 times

Question 7

Sexual reproduction in Paramecium

Answer 7

• Paramecium reproduce sexually by conjugation
• It is define as the temporary union of two morphologically similar but
physiologically different Paramecium to exchange their micronuclear
material
• Paramecium that takes parts in conjugation are called conjugants
(gamatocytes)
• It occurs in unfavorable condition, after several asexual reproduction

Question 8

Process of conjugation

Answer 8

• Paramecium stops feeding so that feeding apparatus disappears from
the body
• The mating paramecium come closer and unite with their ventral
surface with the help of sticky substance secreted by cilia present in
oral surface
• The pellicle and ectoplasm disappears at the point of contact and
protoplasmic bridge is formed in between them (buccal apparatus)
• Macronucleus degenerate and absorbed in cytoplasm
• Micronucleus divide meiotically to form four haploid nuclei
• Out of four haploid nuclei, three are degenerated in each conjugant
• The remaining nucleus divides unequally forming two nuclei
• Among them larger one is called stationary pronuclei and smaller is
called migratory pronuclei
• Stationary pronuclei remain inside the body while migratory pronuclei
are exchange through protoplasmic bridge and fused with stationary
pronuclei of another paramecium to form zygote nucleus (synkaryon)
• The protoplasmic bridge degenerate and conjugant separate with
each other (ex- conjugant)
• The zygote nucleus of each conjugant divide three times repeatedly to
produce eight nuclei
• Among them four nuclei become macronucleus and four is
micronucleus
• Out of four micronuclei, three are degenerated and only one is persist
which divide into two so that each daughter Paramecium have four
macronuclei and two micronuclei
• Each daughter Paramecium now divide by transverse binary fission at
the middle of the body
• So that the newly formed Paramecium have two macronuclei and one
micronucleus
• The micronucleus of each Paramecium again divide into two
mitotically
• After that the Paramecium again undergoes transverse binary fission
forming two Paramecium of each
• So that after completion of conjugation eight Paramecia are formed

Question 9

Significance of conjugation

Answer 9

a. Rejuvenation
• If conjugation does not takes place for long period of time, the
Paramecium weaken and die
• Paramecium restores vitality of the species by conjugation called
rejuvenation
b. Heredity variation
• Mutual exchange of migratory nuclei in conjugation helps to
exchange heredity characters due to which each exconjugants contain
heredity material from two conjugants
c. Nuclear reorganization
• A new macronucleus is formed during conjugation with renewed
potentialities to perform the metabolic activities
d. Formation of new strains
• Daughter Paramecia formed by conjugation are always capable to
sustain themselves in changed environment, hence help in evolution

Question 10

Autogamy

Answer 10

• It is modified form of self fertilization where stationary pronuclei and
migratory pronuclei of same Paramecium fuse to form zygote nucleus
• It is reported in Paramecium aurelia

Question 11

Cytogamy

Answer 11

• It is a type of modified form self fertilization during which two
conjugants get attached with each other and autogamy takes plaace
• But there is no exchange of nuclear material

Question 12

Paramecium caudatum

Answer 12

Kingdom: Protista
Phylum: Protozoa
Class: Ciliata
Genus: Paramecium
Species: caudatum
Common Name: slipper animalcule

Question 13

Habit and Habitat

Answer 13

• Paramecium is a fresh water protozoan, commonly found in ponds,
lakes, reservoirs, etc. Usually they live in the water rich in dead or
decaying materials. So paramecium is also called infusorian
animalcule. The chief food of paramecium is bacteria.
• Paramecium shows holozoic types of nutrition. The chief food of
paramecium is bacteria

Question 14

Body structure:

Answer 14

Paramecium is a microscopic unicellular animal, shaped almost looks
like sole of foot or slipper. So it is commonly called slipper animalcule.

Question 15

Shape, size and color

Answer 15

• The body shaped is fixed due to presence of pellicle layer.
• The size varies between 0.3mm to 0.4mm in length.
• Its anterior end is round and blunt, while its posterior end is
somewhat conical and almost pointed giving it a shape like a sole of
slipper. Therefore, it is also commonly known as slipper animalcule.
• It appears light grey or pale yellowish in colour.

Question 16

External features of Paramecium

Answer 16

1. Pellicle:
   • It is thin, firm, elastic, double layered outer covering of the body.
   • It is made up of gelatin layer (shiny protein layer).
   Function:
   • It provides definite shape to the body.
   • Its flexible and elastic nature allows the animalcule to escape
   (squeeze) through narrow spaces. This process is called metaboly.
2. Cilia:
   • The entire body is covered by numerous fine hairs like processes called
   cilia.
   • The cilia present at the posterior region are long combined to form caudal
   tuft.
   • It helps in changing body direction at the time of swimming.
   Function of Cilia:
   • It helps in locomotion.
   • It also helps to capture food. The cilia near the oral groove filter the large
   food particles and allow smaller food particles inside the cytostome.
   Hence, paramecium is also a filter feeder.
   • It also acts as sensory (tactile) organ.
   ..\Downloads\Amazing Microscopic HD Video! Paramecium
   Feeding!!.mp4
3. Oral groove:
   • It is a large, oblique shallow depression found on the ventral surface.
   • It opens at its base called mouth or cytostome.
   • The mouth immediately extends into a short tract called cytopharynx
   or cell gullet which forms or terminates into food vacuole.
   • When the food vacuole is filled with food, it automatically moves
   within the cytoplasm for digestion and absorption in a clock wise
   direction. The movement of food with food vacuole within the
   cytoplasm or endoplasm is called food cycle or cyclosis.
4. Cytopyge:
   • It is a small opening below
   the oral groove at the ventral
   side.
   • The waste food eject out from
   the temporary opening called
   cytopyge or cell anus.

Question 17

Internal structure of Paramecium:

Answer 17

Internally, the protoplasm is divisible into
outer ectoplasm and inner endoplasm.
I. Ectoplasm: The ectoplasm is densed, strong
part of cytoplasm situated below the pellicle.
• It consists of Trichocysts.
Trichocysts:
• These are tiny, spindle shaped bodies
present in the ectoplasm below the pellicle.
• These are arranged in a row at right angle to
the pellicle.
• Each trichocyst opens outside through a
minute pore just above the pellicle between
two cilia.
• They are filled with transparent, dense
swelling substance called trichinin.
• The trichocyst contain a terminal pointed tip
called spike which is covered with cap.
Function of trichocysts:
• It acts as an organ of offence or defense.
• If a paramecium feels irritated, they discharge this trichocyst as long
elongated sharp needle.
• It also serves as organ of adhesion.
• It anchors the paramecium to a firm substratum, while it is feeding on
bacteria or other unicellular organisms.
II. Endoplasm:
• It is a thin part of cytoplasm. It consists of the following structures:
1. Nucleus 2. Contractile vacuole 3. Food vacuole (gastrioles)
1. Nucleus:
• There are two nuclei almost at the centre of the cell, one nucleus is
large bean shaped called macronucleus or meganucleus. It is not
bounded by nuclear membrane.
• The other is smaller round shaped nucleus called micronucleus. It is
bounded by nuclear membrane. Therefore, Paramecium shows
nuclear dimorphism.
Function:
• The meganucleus controls all the metabolic activities inside the body.
• The Micronucleus controls all the reproductive activities.
2. Contractile vacuoles:
• There are radiating contractile vacuoles, each in the anterior and posterior
regions of the body.
• Each contractile vacuole has radial canals for the collection of excess water and
nitrogen waste of protoplasm.
Function:
• These help in regulation of water content in the body i.e. osmoregulation.
• It also removes carbondioxide from the body.
• It also removes excretory product to the outside and acts as excretory organ.
3. Food vacuoles:
• The food vacuole arises from cytopharynx.
• When the food vacuole is filled with food, it automatically moves
within the cytoplasm for digestion and absorption in a clock wise
direction.
• The movement of food with food vacuole within the cytoplasm is
called food cycle or cyclosis.
• Function: It helps in digestion and absorption of food particles.