studying a) binary fission in amoeba b) budding in Yeast and hydra with the help of prepared slides
Answers
Answer:
Aim
To study binary fission in amoeba and budding in yeast with the help of prepared slides
(a) binary fission in Amoeba Experiment
(b) budding in yeast with the help of prepared slides.
Theory
Reproduction: Plants and animals reproduces (i.e., create new individuals) either by asexual method or by sexual method.
Asexual reproduction: When an organism reproduces by single organism, it is called asexual reproduction. The different ways of asexual reproduction are fission, budding and regeneration in animals.
1. Binary Fission
This is commonly seen in single celled animals. There are no gametes or fertilisation. The cells divide many times through mitosis. Animals like Amoeba reproduce in this manner.
Amoeba is a tiny unicellular organism that has a porous cell membrane, changes its shape constantly and encloses the cell organelles. The genetic material replicate through amitotic division, the cell divides into two equal sized daughter cells. The division of nucleus is called amitosis because the stages of a typical mitotic division are not observed in Amoeba.
Karyokinesis: The division begins with the nucleus dividing to form two daughter nuclei by the process of karyokinesis.
Cytokinesis: Karyokinesis is followed by cytokinesis which is the division of cytoplasm in the mother cell. Two daughter Amoebae cell having a nucleus and its own cell organelles are formed.
2. Budding
In this type of reproduction an outgrowth develops due to repeated cell division on the parent cell that grows to form a bud. The fully grown bud detaches from the mother’s body by forming a constriction at the base and become new individual.
Yeast are unicellular eukaryotic micro-organisms belonging to the kingdom fungi (some are multicellular). They reproduce by budding. Sometimes chain of cells remain attached to the parent cell. When these cells get detached they form a new individual organism.
Materials Required
Prepared slides of Amoeba showing binary fission with different stages.
Prepared slides of yeast showing budding with different stages.
Compound microscopes 2-4.
(A) Binary Fission in Amoeba Procedure
Place the prepared slides of Amoeba showing different stages of reproduction on the stage of the microscope.
Adjust the mirror of the microscope to focus maximum light on the slide. Adjust the eye-piece of the microscope so that the slide is clearly focussed and seen.
Draw diagrams of the stages of binary fission in Amoeba.
NCERT Class 10 Science Lab Manual Binary Fission in Amoeba and Budding in Yeast 1
Observations
Amoeba is a protozoa that lives in water and has irregular shape.
In the centre of Amoeba dense nucleus is seen.
In second stage, Amoeba shows the nucleus division, i.e., karyokinesis.
In third stage, we can see the cell body division, i.e., cytokinesis.
In the fourth stage, two daughter cells of Amoeba are formed.
Conclusion
The given slides showed the division of a single cell body into two equal halves. The division of nucleus and cell body are seen which led to the formation of two daughter cells. Hence, the kind of reproduction seen in Amoeba is binary fission.
(B) Budding in Yeast
Procedure
Place the permanent/prepared slides of yeast showing different stages of reproduction on the stage of microscope.
Make the adjustments in mirror of the microscope for focussing maximum light on the slide.
Adjust the eye-piece so that the slide is clearly seen.
Draw diagrams of the stages of budding yeast cells.
Observations
Yeast is oval or spherical in shape.
It is a unicellular organism.
In the second stage, yeast shows a small growth on it called ‘bud’.
In the third stage, yeast shows that in some situations many such chain of buds is seen on the parent cell. This process is called ‘budding’.
On maturity the buds get separated from parent cell to form and grow’ as a new organism. This process is called budding.
Conclusion
The given slides showed the small growth (bud) on yeast. These buds on maturity separates from parent cell and grow as a new organism, hence, yeast shows budding.
Precautions
(1)Use microscope very carefully. Do not disturb its adjustments.
(2)The slides shown under the microscope should not be disturbed.
(3)Set the mirror of the microscope for better focus of light on the slide.
(4)The slide can be seen under low power or high power of the microscope. These adjustments should be done very carefully.
Asexual reproduction is the type of reproduction observed in lower organisms.
- The principle is that budding and binary fission are types of asexual reproduction that are observed in lower organisms.
- In binary fission, the parent cell divides into daughter cells through mitosis.
- Each daughter cell will become an adult cell.
- In binary fission, new organisms buds out of the parent cell. The bud drops out of the parent cell and develops into an adult cell.
- The procedure: The specimen of amoeba or yeast is placed on the slide.
- The slide is placed under the compound microscope.
- The slide is observed under the lower magnification and then at a higher magnification.
- The process of fission and budding is observed.