Wednesday, March 29, 2017

[Science] - "Reproduction"

Reproduction is a process in which organisms produce their offsprings.

Reproduction in Plants:
1. What is cutting and drafting?
Humans are able to propagate plants by artificial propagation. Taking cuttings and grafting are the methods of artificial propagation which you need to know. They are a quick way of propagating large numbers of identical plants, so they look the same towards each other.

2. What is a clone?
A clone is a group of cells or organisms which are genetically identical to each other.

3. What are the advantages of asexual reproduction in plants?
  1. Only one parent plant is required
  2. Young plants are identical to the parent, so that good features will always be passed on.

Reproduction is of two types:
Two Types-  Asexual & Sexual:
1. Asexual reproduction:
In this type of reproduction only one organism (parent) or part is required and new organism is produced like unicellular organisms.

2. Sexual reproduction:
In this type of reproduction two organisms (male & female) takes part and new organisms are formed like in all multi-cellular organisms.

Asexual reproduction is found in plants and animals.

Vegetative propagation: It is a type of asexual reproduction in which any part of the organism develops into a new organisms like budding & fragmentation.

In plants stem, leaf or root develops into a new plant for example… stem in mint, onion & potato can grow into a new plant.

Vegetative propagation in plants is used to produce high yielding and better quality of fruits & vegetables.

In animals sometimes they reproduce by fragmentation for spore formation where only single organism produces new organism.

1. Brief definition of "Reproduction"
The definition of reproduction is the action or process of creating another form of something, as in duplicating or copying of the same form. Example; Human beings make youngs which are “babies”, Animals such as cats create another form of itself which we call “kittens.” That is the outcome of reproduction. Reproduction is when new organisms are generated, it is the process of species continuation of it’s existence. There are two means of reproducing such as Asexual and Sexual.  

2. What is sexual & asexual reproduction?

Sexual Reproduction:
A type of reproduction that is needed of two individuals of different gender (sexes) combining to form another individual. Does not involve sex cells or gametes

Asexual Reproduction:
A type of reproduction in which the fusion of gametes is not included, so it’s not needed. Offspring arises, as an individual is formed from a single organism. It is the formation of a new individual from the cell of a single parent.

3. Give examples of asexual reproduction in plants & animals:
Animals= reproduce sexually by gametes that are produced that join in fertilisation. Plants= reproduce asexually through the roots such as corns and stem tubers. Some plants can produce seeds without fertilisation, where the ovule or ovary gives rise to new seeds it self.

4. Give example of sexual reproduction in plants & in plants & animals:
Plants= reproduce sexually through flowering plants, in which has organ like genetics within the flower, which is The Carpels and The Stamen.
Animals= reproduce asexually through fission, budding & fragmentation.

5. What are the advantages & disadvantages of asexual reproduction?
It promises reproduction and is able to create individuals very fast and comes in large amount. Because there’s no more sexual reproduction, you don’t need sperm nor egg.

For the male gamete to meet the female gamete, it needs water, because of an asexual reproduction it is not needed. An asexual reproduction, population intends to be genetically static. Because they're all the same - having all the same characteristics, for example; a plant can only withstand about 7 degrees for them to be able to live, if the temperature goes less than 7 degrees, they will die.

6. What are the advantages & disadvantages of sexual reproduction?
Characteristics are inherited from two parents. This  variation in the offspring. In changing the environment, this gives a good chance of at least a few to survive, for example; diseases and etc. Not all of them will die but the ones that are able to cope with the climate changes, they are most likely to survive. So like, the ones that had survived, they have the tolerance.

-Seeds/fruit are formed and is allowed for long distance dispersal

If there are too much variation prevents close adaptation to any given environment, which produces large numbers of gametes and is wasteful since a lot of them will die in stressful environments. The offsprings that inherit the genes who can’t tolerate, they are most likely to not survive.

  • Characteristics are inherited from two parents - this produces variation in the offspring;
  • This gives a good chance of at least a few surviving diseases, changes of climate, etc.
  • “Jack of all trades, Master of none.”
Defines those who are good at a lot of things and those who aren’t.

Questions On Reproduction:
Look at the picture of a grass flower...
Grass flower with labelled structures - feathery stigma which hangs outside the flower, and the stamen which consists of the anther, held up by a long filament.
(a) Is this flower insect or wind pollinated?
Answer: Wind pollinated

(b) Name a structure which is absent or not labelled on this flower which would be significant in flowers which use the other method of pollination.
Answer: Large colourful petals/nectary

(c) Choose one feature of the stamen, and one feature of the stigma which are shown on the diagram and explain how each feature helps with the plant’s method of pollination.
Answer: The stigma is feathery in shape. This gives it a very large surface area for catching pollen grains blowing in the wind. It is also hanging outside the rest of the flower so that it is in the best place to catch drifting pollen. The anther is large and hangs outside the flower. This means that it can produce lots of pollen and that it will be efficiently released into the air.

(d) Name a plant which reproduces asexually by means of runners and give a brief description of how this is achieved…

Answer: Strawberries. Runners are side shoots which grow out from the parent plant and form buds at points along the runner; the buds form roots and grow into new plants.

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