CBSE Class 10 Biology Practical Skills

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CBSE Class 10 Science  (Biology) Practical Skills – 
Binary Fission in Amoeba and Budding in Yeast

BASIC BUILDING CONCEPTS
Reproduction is the ability of an individual to produce new generation of individuals of same species.
It involves the transmission of genetic material from the parental generation to the next generation, thereby ensuring that characteristics, not only of the species but also the parental organisms, are perpetuated.

Types of Reproduction
Reproduction is of two types – Asexual and Sexual.

Asexual reproduction – 
Production of offspring by a single parent without the involvement of gamete formation is called asexual reproduction. The off springs produced by asexual reproduction are identical to parents. Such identical off springs from a single parent are referred to as clone.
Asexual reproduction is of various types which are listed in the following flow chart.

Sexual reproduction – 
Sexual reproduction involves two parents. Male parent produces male gametes and female parent produces female gametes. Male and female gametes fuse together to form a zygote. Zygote is the first cell of next generation.

AIM
* To study binary fission in Amoeba, and
* Budding in yeast with the help of prepared slides.

MATERIALS REQUIRED
Compound microscope, permanent slides of binary fission in Amoeba and budding in yeast.

THEORY

Binary Fission This is a type of asexual reproduction which takes place in Amoeba. In this type of reproduction, parent cell divides into two small, nearly equal sized identical daughter cells. The two daughter cells then grow into adult organism. In binary fission parental identity is lost.

Budding – This is also a type of asexual reproduction which is common in yeast. In this type of reproduction a small bud-like outgrowth develops at the parent cell. This bud enlarges in size. The nucleus also enlarges in size and divides to form two nuclei. Out of these two nuclei, one goes into developing bud. When the bud attains almost the same size as that of parent cell, a separating wall is laid down between the bud and parent cell. This bud may detach from the parent cell or may produce another bud over it.

PROCEDURE
(1) Select the slide of binary fission in Amoeba and budding in yeast.

(2) Set-up a compound microscope. While looking through the eye piece, adjust the mirror and diaphragm so that microscope is illuminated.

(3) Now, place the slide on stage and focus at low power. Observe it.

(4) Without removing the slide, now change the focus to high power. Observe it.

OBSERVATIONS
(a) Binary Fission in Amoeba

* This is a type of asexual reproduction in which two daughter cells (or two individuals) are formed from a single parent.

* Parent cell becomes elongated.

* Nucleus divides first and then the cytoplasm divides.

" At the point of fission, constriction appears and deepens to divide the cell into two daughter cells.
b) Budding in Yeast
" In this type of asexual reproduction, a small protuberance or outgrowth arises from the parent body called bud.

* Nucleus divides to form two daughter nuclei, of which one passes into the bud.

* The bud now detaches from the parent body and grows independently as a new individual or may remain attached to parent body, forming chain of cells.

* Parental identity is not lost.
RESULT
The slides show reproduction by binary fission in Amoeba and budding in yeast.

PRECAUTIONS
Always focus the slide, first at low power and then at high power.
While focussing at high power, do not use coarse adjustment of microscope. Only use fine adjustment.

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           NTERACTIVE SESSION

Question 1.
What is reproduction?
Answer:
Reproduction is the process by which individuals produce offsprings of their own species.

Question 2.
What are the types of reproduction?
Answer:
Reproduction is of two types-
* Sexual reproduction
* Asexual reproduction.

Question 3.
Define sexual reproduction.
Answer:
Sexual reproduction is the production of offsprings by the fusion of two gametes to form a zygote which develops into a mature organism.

Question 4.
What is asexual reproduction?
Answer:
Asexual reproduction is the production of offsprings by a parent without fertilisation and formation of gametes.

Question 5.
Differentiate between asexual and sexual reproduction.
Answer:
Question 6.
Out of sexual and asexual reproduction, which one leads to more variations among offsprings. Why?
Answer:
Sexual reproduction leads to variations as it involves fusion of gametes and crossing over of chromosomes during gamete formation.

Question 7.
What is binary fission?
Answer:
Binary fission is a type of asexual reproduction in which parent cell divides amitotically to form two daughter cells. In cell division, first the nucleus divides and then the cytoplasm.

Question 8.
How is binary fission different from multiple fission?
Answer:
In binary fission, one cell divides to form two daughter cells, whereas in multiple fission, one cell forms several daughter cells.

Question 9. Oo
Why do we classify budding, fission or fragmentation as a type of asexual reproduction?
Answer:
All these are categorised as types of asexual reproduction as they all involve one single parent and no gamete formation takes place.

Question 10.
Give examples of organisms which show the following –
* Binary fission
* Budding.
Answer:
Examples of organisms which reproduce by binary fission are – Amoeba, Paramoecium, Euglena.
Examples of organisms which reproduce by budding are – Yeast, Hydra.

Question 12.
Define budding.
Answer:
Budding is a type of asexual reproduction in which a small outgrowth or protuberance called bud appears. Bud may or may not separate from parent body.

Question 13.
Distinguish between budding in yeast and budding in Hydra.
Answer:
Yeast is a unicellular fungi. The bud formed is unicellular and may remain attached to parent cell, whereas bud in Hydra is multicellular and appears as branch. This branch separates from parent body and grows as separate individual.

Question 14.
Name the most common method of reproduction in yeast.
Answer:
Budding.

Question 15.
Name the type of cell divisions involved in asexual reproduction.
Answer:
Amitosis and mitosis.

Question 16.
What is vegetative propagation?
Answer:
It is a method of asexual reproduction in which a vegetative part of plant is used to produce new individual.

Question 17.
Give one term for the division of nucleus.
Answer:
Karyokinesis.

Question 18.
Offsprings formed by asexual reproduction are called clones. What are clones?
Answer:
All individuals which are morphologically and genetically similar to each other and are derived from a single parent are called clone.

Question 19.
What are spores?
Answer:
A spore is a small unit involved in asexual reproduction. These are microscopic, unicellular structures which contain small amount of cytoplasm and nucleus.

Question 20.
Amoeba is immortal. Comment.
Answer:
Amoeba divides into two by binary fission, each grows to live and no dead body is left.

Question 21.
Which organisms have better survival value-asexually or sexually reproducing?
Answer:
Sexually reproducing organisms have better survival value as they show more variations.

Question 22.
What are the advantages of asexual reproduction?
Answer:
Advantages include

* Offsprings are identical to the parents.

"Rapid multiplication of organisms.

*Vegetative propagation is the only method of reproduction for plants which does not produce viable seeds.

LAB MANUAL QUESTIONS

Question 1.
Which type of cell division is involved in binary fission?
Answer:
Mitosis

Question 2.
How many daughter cells are formed in binary fission?
Answer:
Two

Question 3.
Why are binary fission and budding included under asexual reproduction?
Answer:
* Only one parent is involved.
* Offsprings are genetically identical.

Question 4.
Are binary fission and budding faster process of reproduction when compared to sexual reproduction. Justify.
Answer:
Yes, as by simple cell division, daughter cells are formed. In sexual reproduction, formation and fertilisation of gametes are involved

PRACTICAL BASED QUESTIONS

Multiple Choice Questions  (1 Mark)

Question 1.
The figures given above are drawn from slides showing reproduction in yeast and Amoeba. The correct description of the above is 
(a) Amoeba undergoing binary fission is at a ; stage when nucleus is elongating, while yeast is undergone budding.
(b) Yeast is undergoing binary fission and ;
daughter nuclei have already formed, while a j newly formed daughter Amoeba is undergoing growth.
(c) The nucleus of a parent Amoeba is undergoing ; division to pass into its bud while yeast has j already divided into two daughter cells.
(d) Amoeba is undergoing cytokinesis and Yeast is undergoing budding.

Question 2.
After observing slides showing stages of j reproduction in Amoeba and yeast, students j reported the following observations.
(i) Cytokinesis was seen in the yeast cell.
(ii) A chain of buds was seen due to reproduction in Amoeba.
(iii) In Amoeba, elongated nucleus was dividing to form two daughter nuclei.
(iv) Single cells of Amoeba and yeast were undergoing binary fission and budding respectively.
The correct observations are
(a) (i) and (ii) only
(b) (ii) only
(c) (iii) and (iv) only
(d) (i), (iii) and (iv) only

Question 3.
A chain of yeast cells are formed because 
(a) yeast cells do not separate after budding
(b) daughter cells are unable to survive without parent cells
(c) buds reproduce as soon as they are formed
(d) daughter cells stick together with the help of mucus

Question 4.
Out of the following diagrams which one depicts a stage in binary fission of Amoeba?
(a) A
(b) B
(c) C
(d) D

Question 5.
The following figures illustrate binary fission in Amoeba in an incorrect sequence.
The correct sequence is :
(a) (i), (iii), (iv), (ii)
(b) (ii), (iii), (iv), (i)
(c) (iv), (iii), (ii), (i)
(d) (iii),(iv),(ii),(i)

Question 6.
Four stages of binary fission in Amoeba are shown below. The stage at which nuclear fission and cytokinesis both are observed is, the stage.
(a) I
(b) II
(c) III
(d) IV

Question 7.
Out of the given diagrams, the correctly labelled diagram showing budding in yeast is 
(a) I
(b) II
(c) III
(d) IV

Question 8.
Name the type of asexual reproduction in which parental identity is maintained.
(a) Multiple fission
(b) Binary fission
(c) Budding
(d) All of these

Question 9.
During binary fission in Amoeba, which of the following occurs first?
(a) Cytokinesis
(b) Karyokinesis
(c) Both (a) and (b), simultaneously
(d) None of these

Question 10.
In the slides showing binary fission in Amoeba and budding in yeast, the correct observations are [Delhi 2007C]
(a) the daughter cells of Amoeba and the bud of yeast are smaller than their respective parental cells.
(b) the daughter cells of Amoeba and the bud of yeast are of the same size as their respective parental cells.
(c) the daughter cells of Amoeba are bigger than the parent but bud of yeast is smaller than the parent.
(d) the daughter cells of Amoeba are smaller than the parent but bud of yeast is larger than parent.

Question 11.
A student observed a slide of yeast under a microscope and saw collection of cells in different parts of the slide marked A, B, C and D as shown below. Which one of the following parts of the slide shows budding in yeast? 
(a) A
(b) B
(c) C
(d) D

Question 12.
Mention sequence of budding
Correct sequence is
(a) A, B, C, D
(b) A, D, B, C
(c) C, A, B, D
(d) D, A, B, C

Question 13.
What do F and E represent in the given diagram?
(a) Parent yeast cells
(b) Daughter Amoebae
(c) Yeast buds
(d) Parent Amoebae

Question 14.
Which of the following is not a feature of asexual reproduction?
(a) Two individuals of different sexes involved.
(b) No meiosis occurs.
(c) New individuals are genetically identical to the parents. .
(d) Offsprings are clones of parents.

Question 15.
From the following diagrams, select the correct ones showing stages of binary fission in Amoeba and budding in yeast in their proper sequence
a) 5, 1, 4 and 2, 3, 6
(b) 3, 4, 7 and 2, 8, 6
(c) 7, 4, 1 and 3, 8, 6
(d) 8, 7, 4 and 3, 2, 6.

ANSWER KEY (MCQ)

1.(a)
2.(c)
3.(a)
4.(d)
5.(b)
6.(b)
7.(b)
8.(c)
9.(b)
10.(a)
11.(b)
12.(a)
13.(b)
14.(a)
15.(c)

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