How do Organisms Reproduce-1 Flashcards
why do organisms reproduce
- organisms reproduce in order for their species to survive.Reproduction is an essential process required for continuity of life and survival of species generation after generation.
An individual has a limited lifespan and lives for a defined time period but species survive and evolve for a much longer duration.
-evolution, it allows their species to modernise and adapt to any changes in their niches
why is reproduction not a life process
All living organisms have the feature or character of reproduction. This is an important life process that not only helps in survival but also helps in the continuity of that race and group immortality, as by reproduction. Reproduction also helps in increasing the population of the species. All the processes which are necessary to maintain life in an organism are called life processes. Reproduction is not considered a life process because it is not necessary to maintain life.
what is dna? where is it present?
DNA( deoxyriboNucleic acid) is a molecule present in the nucleus. It is found in the chromosomes in the nucleus of cells.it holds the instructions for making all the proteins in our bodies.
what does dna contain
The dNA contains the information of inheritance of features form the parents to the next generation. It also contains, the information source for making proteins. If the information is changed, then different proteins will be made and different proteins will lead to altered body designs.
what is the most important event in reproduction?
a basic event in reproduction is the creation of a DNA
copy.
explain in brief how a cell splits into 2
Cells use chemical reactions to build copies of their DNA. This
creates two copies of the DNA in a reproducing cell, and they will need to
be separated from each other. However, keeping one copy of DNA in the
original cell and simply pushing the other one out would not work,because the copy pushed out would not have any organised cellular
structure for maintaining life processes. Therefore, DNA copying is
accompanied by the creation of an additional cellular apparatus, and
then the DNA copies separate, each with its own cellular apparatus.
Effectively, a cell divides to give rise to two cells
are the two cells always identical?
it depends upon the accuracy of the copying reaction. no bio-chemical reaction is fully reliable. so we can assure that the process of copying dna alwaystends to have some variation.As a result, the
DNA copies generated will be similar, but may not be identical to the
original. Some of these variations might be so drastic that the new DNA
copy cannot work with the cellular apparatus it inherits. Such a newborn
cell will simply die. On the other hand, there could still be many other
variations in the DNA copies that would not lead to such a drastic
outcome. Thus, the surviving cells are similar to, but subtly different
from each other. This inbuilt tendency for variation during reproduction
is the basis for evolution.
define a niche
niche is a well-defined space to whcih an organism has adapted itself to
bring a link between stability of population and reproduction
In reproduction process, dna is copied and passed down the next egenration along with the cellular apparatus.
The consistency of DNA
copying during reproduction is important for the maintenance of body
design features that allow the organism to use that particular niche.
Reproduction is therefore linked to the stability of populations of species.
explain with an example why is variation necessary
niches can change because of reasons beyond the control
of the organisms. Temperatures on earth can go up or down, water levels
can vary, or there could be meteorite hits, to think of a few examples. If
a population of reproducing organisms were suited to a particular niche
and if the niche were drastically altered, the population could be wiped
out. However, if some variations were to be present in a few individuals
in these populations, there would be some chance for them to survive.
Thus, if there were a population of bacteria living in temperate waters,
and if the water temperature were to be increased by global warming,
most of these bacteria would die, but the few variants resistant to heat
would survive and grow further. Variation is thus useful for the survival
of species over time.
Discuss what is the importance of DNA copying in reproduction?
i)DNA contains the blueprints for how to make the proteins and other molecules that make the cell run. The cells would not be able to make molecules without it and they would not be able to survive, and thus would die.
ii) It is important to copy the DNA in order to maintain equal distrubution of genetic material in resulting offsprings.
iii)copying of DNA helps in the transfer of information or characters from parents to offspring.
define sexual reproduction
Process of creating new individual using two parent organisms
describe in brief what is sexual reproduction
Sexual reproduction requires two parents. Each parent contributes a gamete - a sex cell that has half of the normal DNA of a regular body cell. In males, the gametes are sperm and in females, the gametes are eggs.
When these two gamete combine during fertilization, the result is a zygote, which then continues to develop into an embryo.
define asexual reproduction
Process of creating new individual using one parent organism
differentiate between sexual and asexual reproduction
Sexual Asexual
Requires 2 parents Requires 1 parent
Sperm fertilizes egg Single organism makes an exact copy of itself
Used by animals, flowering plants, some fungi Bacteria, some plants and fungi, few animals (sponges)
Offspring are different from parents Offspring are identical to parent
Provides genetic variation, but time-consuming Fast and easy, but no genetic variation
