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How Do Organisms Reproduce? - 1

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Sporangium develops on slender, erect, thread-like structures called

  1. constrictions

  2. spores

  3. buds

  4. hyphae


Correct Option: D
Explanation:

The thread-like structures on which sporangia develop are called hyphae. Their scientific name is sporangiophore.

Which of the following methods can be used to produce 'disease-free plants’?

  1. Grafting

  2. Layering

  3. Cutting

  4. Tissue culture


Correct Option: D
Explanation:

Disease-free plants can be produced by tissue culture. In this technique, we can take few healthy cells and selectively multiply them to form new plants under sterile and aseptic conditions. But, in grafting or layering or cutting, the chances of having diseased plants are there because the cells cannot be selectively chosen in these and at any time, the pathogens may attack them.

Which part of a plant does not take part in vegetative propagation?

  1. Root

  2. Stem

  3. Leaf

  4. Flower


Correct Option: D
Explanation:

Vegetative propagation means formation of new plants from vegetative parts.

Which of the following plants does not produce seeds?

  1. Apple

  2. Pear

  3. Peach

  4. Banana


Correct Option: D
Explanation:

We know that apple, pear and peach have seeds. It is only banana that is seedless and has lost the capacity to produce seeds. In case of apple, the ability to produce seeds is there but they may not be viable.

Binary fission occurs during _______.

  1. favourable conditions

  2. unfavourable conditions

  3. hot conditions

  4. humid conditions


Correct Option: A
Explanation:

Binary (Bi means two) fission produces only two daughter cells and occurs repeatedly, generation after generation, in short time intervals. This fast reproduction is possible only under favourable conditions of temperature, food and humidity. But under unfavourable conditions like high or low temperature, low humidity or lack of food, multiple fission occurs.

If hydra is cut into two parts, it does not die because _________.

  1. it can form a bud

  2. it can regenerate into two complete organisms

  3. it can produce spores

  4. the two parts are new individuals


Correct Option: B
Explanation:

On being cut, the two parts of hydra can regenerate the other part because it is a simple organism. Bud also helps it in reproduction, but on being cut, regeneration ability plays the role. The two parts cannot be two individuals unless they regenerate. Lastly, hydra does not produce spores as it reproduces by budding.

Which of the following cells helps to carry out regeneration?

  1. broken cells

  2. normal cells

  3. specialized cells

  4. differentiated cells


Correct Option: C
Explanation:

Regeneration is carried out by specialized cells, which can proliferate at a fast rate. Also, they can form all the different cells that are required to form the body part that the organism needs to regenerate. Broken cells may not proliferate while “all cells” cannot have the above mentioned specialized features. Differentiated cells take up a fixed role and may not be able to produce all the cells required in regeneration.

The ability of an organism to develop into a whole body from a broken piece is known as ___________.

  1. budding

  2. regeneration

  3. fusion

  4. fission


Correct Option: B
Explanation:

To develop a whole body from a fragment is possible by proliferation (i.e. repeated division and consequent growth) of cells. This is called regeneration. On the contrary, in budding, a complete organism forms a new individual from a bud, and in fission, the cells divide into two. Fusion is said to occur when two cells combine to mix their traits (like in bacteria) and it is uncommon.

Spores are produced inside the round blob-like structures known as __________.

  1. sporangia

  2. capsule

  3. cyst

  4. bud


Correct Option: A
Explanation:

Spores are the microscopic structures formed during the life cycle of many fungi. Each spore, upon falling on suitable substratum (medium on which an organism depends for deriving its food), grows into a complete organism, which can later divide and form a complete colony. Spore-bearing structures are called sporangia and they are present on stalks called sporangiophores. Capsules refer to dry and indehiscent fruits. When they split, seeds fall out from them. Cysts are hard covered bodies formed under unfavourable conditions in bacteria and they produce daughter cells, and not spores. Similarly, buds also do not bear spores as buds are bulging outgrowths of the parent body which, after maturation, detaches itself from the parent body and develops into a new individual. Buds and spores are two different means of asexual reproduction.

The mode of reproduction in Leishmania, the organism which causes kala–azar in humans, is called

  1. binary fission

  2. multiple fission

  3. Both (1) and (2)

  4. None of these


Correct Option: A
Explanation:

Leishmania has a specific organisation of body. It has a whip-like flagella on one end. Due to this, when its fission occurs, it divides the body such that both get the flagella (duplicated). This is possible in binary fission, but not in multiple fission, which will require the division to occur in different planes.

Which of the following processes helps to produce plasmodium?

  1. binary fission

  2. multiple fission

  3. regeneration

  4. spore formation


Correct Option: B
Explanation:

Plasmodium grows rapidly inside a human body and for this, it divides by multiple fission because binary fission will produce less number of organisms. Since it is a unicellular organism, so regeneration and spore formation do not occur in Plasmodium.

Which of the following modes of reproduction is an example of sexual reproduction?

  1. Fission

  2. Gamete formation

  3. Regeneration

  4. Spore formation


Correct Option: B
Explanation:

Sexual reproduction involves two parents and their gametes fuse to form a new individual. Thus, formation of gametes is a part of sexual reproduction. Fission, regeneration and spore formation are all asexual methods of reproduction.

Which of the following techniques can be used to propagate 'Ornamental plants'?

  1. Budding

  2. Fragmentation

  3. Tissue culture

  4. Regeneration


Correct Option: C
Explanation:

Ornamental plants are very delicate and some of their features make them valuable. It is desired that during their propagation, there should be no change in those traits and also they should remain free from any disease. Both these requirements are met by tissue culture technique. In addition, it helps to produce a large-scale commercial yield. Budding, fragmentation and regeneration cannot serve all these purposes together because they are slow and cannot ensure disease free progeny.

Which of the following options is not a feature of asexual reproduction?

  1. The offspring is an identical copy of the parent.

  2. All the divisions are mitotic in nature.

  3. It takes longer period of time than sexual reproduction.

  4. It involves a single individual only.


Correct Option: C
Explanation:

Asexual reproduction involves only one parent and its cells divide by mitosis (without any change in chromosomes number). Thus, there is no change in genetic makeup of new cells, and the offsprings are identical to parents. Since this method of reproduction involves simple cell division (without any change in number or traits of chromosomes), so it is faster than sexual method. Thus, here only option (3) is incorrect.

Which type of asexual reproduction takes the least time?

  1. Multiple fission

  2. Regeneration

  3. Spore formation

  4. Binary fission


Correct Option: D
Explanation:

Multiple fission, regeneration and spore-formation, all require the formation of a large number of new cells by repeated division of initial or few cells. But in binary fission, only one division occurs and produces two daughter cells. Thus, binary fission is the fastest mode of reproduction. In fact, cells are known to produce daughter cells in twenty minutes of time from their own birth by binary fission.

The biochemical basis of reproduction is __________.

  1. RBC

  2. WBC

  3. neuron

  4. DNA


Correct Option: D
Explanation:

At the cellular level, reproduction refers to the formation of new cells. It can occur, if a new cell gets nucleus and nucleus contains DNA molecules. DNA is the genetic material, which is passed from one generation to another. Thus, for reproduction, DNA material is to be duplicated. Hence, DNA is the biochemical basis of reproduction. On the contrary options (1), (2) and (3), which refer to different cells like RBC, WBC and neuron have no role in the process of reproduction.

Which of the following parts of bryophyllum plant helps in vegetative propagation?

  1. Roots

  2. Leaves

  3. Stem

  4. Flowers


Correct Option: B
Explanation:

The leaves of Bryophyllum plant help in vegetative propagation. The notches of these leaves contain vegetative buds, which can grow to produce roots and small shoots that later make a new plant. Its roots, stem or flowers have no such vegetative buds to take part in the reproduction process.

‘Bread mould’ reproduces by

  1. spore formation

  2. regeneration

  3. fission

  4. budding


Correct Option: A
Explanation:

'Bread molds' are a type of fungi and reproduce by spore formation. In asexual reproduction, the mold makes spores inside a sporangium. When the spores are ready to leave and spread more molds, the sporangium breaks open and lets the spores float out. In sexual reproduction, its hyphae touch the hyphae of another Rhizopus mycelium. When they fuse, they make round balls called zygospores. After some time, the zygospore makes another sporangium, which then makes spores. During this sexual process, genetic recombination takes place, as with all eukaryotes. 

Which of the following asexual modes of reproduction is used by the higher plants?

  1. Spore formation

  2. Vegetative propagation

  3. Budding

  4. Regeneration


Correct Option: B
Explanation:

Higher plants have complex structures and they have specialised parts to perform asexual (vegetative) reproduction. For example, leaves, stem, roots, etc. This formation of new organism from vegetative parts of a plant is called vegetative propagation. On the contrary, spore formation, budding and regeneration are reproductive methods found in lower organisms or plants.

An unorganized mass of cells that gives rise to a whole new plant in tissue culture is termed as

  1. rootlet

  2. shootlet

  3. plantlet

  4. callus


Correct Option: D
Explanation:

An unorganized mass of cells is called callus. When it is treated with suitable hormones, it forms tiny root and shoot, which are called rootlet and shootlet, respectively. At this stage, it is called a plantlet.

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