How do Organisms Reproduce- Asexual Reproduction

Question 1

define fission

Answer 1

fission refers to splitting of a cell into two or more daughter cells. It is also known as cell division

Question 2

why is simple cell division the reason for reproduction in unicellular beings

Answer 2

Because the splitting of a single parent cell, gives two (or more) duaghter cells,i.e., offsprings, it is a form of reproduction.

Yes, because it results in the formation of two daughter cells,
that is, it results in the production of more individuals of the
organism

Question 3

what are the types of fission

Answer 3

-binary and multiple fission

Question 4

describe binary fission

Answer 4

binary fission is the splitting of the cell into two daughter cells. There are two types of binary fission.
One type of fission involves the splitting of cells into halves along multiple planes. This takes place in amoeba which doesn’t have a defined body shape. However, there is another type in which the organisms can split into across only one plane. for example, leishmania which has a whip liek structure. Since this also needs to split into two, the leishmania cell can divide across only one plane.

Question 5

describe multiple fission

Answer 5

in this type of fission, the cell is divided into more than two daughter cells simultaneously. This takes place in plasmodium which is the protozoan causing malaria. the protozoan’s nucelus splits underfavourable conditions to form multiple nuclei in a cyst. Cytoplasmic division occurs and each cytoplasmic bit encloses a nuclei. This cyst then breaks and releases daughter cells/.

Question 6

explain the working of fragmentation in spirogyra

Answer 6

Spirogyra, for example,
simply breaks up into smaller pieces upon maturation. These pieces or
fragments grow into new individuals.

Question 7

why cant highly organised multicellular organisms reproduce by simple reproductive methods

Answer 7

This is not true for all multi-cellular organisms. They cannot simply
divide cell-by-cell. The reason is that many multi-cellular organisms, as
we have seen, are not simply a random collection of cells. Specialised
cells are organised as tissues, and tissues are organised into organs,
which then have to be placed at definite positions in the body. In such a
carefully organised situation, cell-by-cell division would be impractical.
Multi-cellular organisms, therefore, need to use more complex ways of
reproduction.

Question 8

what kind of methods do highly organised multicellular organisms use for reproduction

Answer 8

A basic strategy used in multi-cellular organisms is that different
cell types perform different specialised functions. Following this general
pattern, reproduction in such organisms is also the function of a specific
cell type.

Question 9

How is reproduction to be achieved from a single cell type, if
the organism itself consists of many cell types?

Answer 9

there must be a single cell type which is capable of growing, proliferating and making new cell types under the right circumstances

Question 10

define regeneration

Answer 10

When some organisms are cut into different parts, then each part will grow into a new individual. This process of regrowing a body from a fragment is called regeneration

regeneration is the process of repairing an injured body part or replace the lost the ones by accident

Question 11

how is the process of regenration carried out? which cells aid the process and how?

Answer 11

Regeneration is carried out by specialised cells(neoblast/regenerativecells). These cells proliferate
and make large numbers of cells. From this mass of cells, different cells
undergo changes to become various cell types and tissues. These changes take place in an organised
sequence referred to as
development.

Question 12

is regeneration a type of reproduction? why or why not?

Answer 12

However,
regeneration is not the same
as reproduction, since most
organisms would not
normally depend on being cut
up to be able to reproduce. For example, a lizard. When a lizard’s tail is cut, the lizard will grow back its tail. But a new lizard will not grow from the cut up tail. So it is not always reproduction.

Question 13

explain the process of budding in hydra

Answer 13

Organisms such as Hydra
use regenerative cells for
reproduction in the process of
budding. In Hydra, a bud
develops as an outgrowth due
to repeated cell division at one
specific site (Fig. 8.4). These buds develop into tiny individuals and when
fully mature, detach from the parent body and become new independent
individuals.

Question 14

how is budding in yeast different from binary fission

Answer 14

During binary fission, the parent cell splits or divides into two daughter cells. The parent cell does not remain. However, in budding, the parent yeast cell develops a bud which when fully mature detaches itself from the parent cell. Thus we have a daughter and a parent yeast cell. So the binary fission and budding in yeast are different.

Question 15

explain the structure of function of rhizopus

Answer 15

The thread-like structures that developed on
the bread in Activity 8.2 above are the hyphae of the bread mould
(Rhizopus). They are not reproductive parts. On the other hand, the
tiny blob-on-a-stick structures are involved in reproduction. The
blobs are sporangia, which contain cells, or spores, that can
eventually develop into new Rhizopus individuals

Question 16

how does spore formation carry out the process of reproduction

Answer 16

The sporangia, when the rhizopus is mature, will open up and release the spores. These spores will settle down and develop into rhizopus under warm and moist conditions.

Question 17

what is the function of the thickwall covering around spores

Answer 17

The spores
are covered by thick walls that protect them until they come into
contact with another moist surface and can begin to grow.

Question 18

define spores

Answer 18

spores are reproductive cells which are able to give rise to new organisms under favourable conditions.

Question 19

what is vegetative propogation in plants

Answer 19

it is an asexual reproduction in plants that does not use seeds. It involves the use of the vegetative parts of the plant- stem, roots and leaves.

Question 20

explain the process of vegetative propogation

Answer 20

in this method, the cutting of any vegtative part of the plant ( either stem/root/leaf cutting) is sown in the soil, which will grow under suitable conditions( enough sunlight,water and nutrients) and give rise to the plant.

Question 21

why is vegetative propogation called so

Answer 21

In vegetative propagation, new plants are produced from roots, stems, leaves and buds. Since, asexual reproduction is done through the vegetative parts of the plant, it is known as vegetative propagation.

Question 22

explain the vegetative proprogation taking place in bryophyllum

Answer 22

Tips of the notches of the leaf margin of the bryophyllum have little buds, which grow into small tiny plants called plantlets, with their own roots and leaves. These plantlets then fall down and develop as a new individual bryophyllum plant.

Question 23

give the advantages of vegatative propogation

Answer 23

• It helps in the reproduction of plants that have lost their capacity to make viable seeds such as roses, bananas,orange and jasmine.
• it allows the desired traits to be passed along as all plants produced are
  genetically similar enough to the parent plant to have all its
  characteristics.
  -It can bear fruits and flowers earlier than in the plants grown from seeds as the germination period is skipped in vegetatively propgated plants.

Question 24

what is vegetative propogation used for

Answer 24

vegetative propagation is used in methods such as layering
or grafting to grow many plants like sugarcane, roses, or grapes for
agricultural purposes.

Question 25

explain the tissue culture

Answer 25

In tissue culture, new plants are grown by removing tissue or separating cells from
the growing tip of a plant. The cells are then placed in an artificial medium where they
divide rapidly to form a small group of cells or callus. The callus is transferred to
another medium containing hormones for growth and differentiation. The plantlets
are then placed in the soil so that they can grow into mature plants. Using tissue
culture, many plants can be grown from one parent in disease-free conditions. This
technique is commonly used for ornamental plants.