Pre fertilization - plants - class-XII
Description: pre fertilization - plants | |
Number of Questions: 67 | |
Created by: Tanuja Atwal | |
Tags: sexual reproduction in flowering plants modes of reproduction asexual and sexual reproduction in plants life processes in living organisms- part 1 biology cell - the structure and functions reproduction in flowering plants botany cell theory, cell specialization, and cell replacement |
What is the function of germ pore?
-
Emergence of radicle
-
Absorption of water for seed germination
-
Initiation of pollen tube
-
All of these
One or more thin areas present in the exine of pollen grains are known as germ pores. The germ pores are apertures in the exine layer of the pollen grain where the sporopollenin is absent. The germ pore helps in the formation of the pollen tube and the release of the male gametes during fertilisation. There are usually three germ pores in dicots(tricolpate) and one in monocots(monocolpate).
In Casuarina, fertilization occurs by
-
Chalazogamy
-
Mesogamy
-
Porogamy
-
Apogamy
- Pollen tube eventually reaches the micropyle of an ovule to enter the embryo sac and for this purpose, it may follow one of the following three routes:
- 1. Porogamy- when the pollen tube enters the ovule through the micropyle. It is common for most of the angiosperms.
- 2. Mesogamy- when the pollen tube enters through the integuments (Cucumber) or through funiculus (Pistacia).
- 3. Chalazogamy- when the pollen tube enters through the chalazal tissues. For example, Casuarina.
- So, the correct answer is 'Chalazogamy'.
Chalazogamy occurs in
-
Cucurbita
-
Lily
-
Populus
-
Casuarina
The phenomenon of pollen tube entering the ovule laterally through integuments is called
-
Mesogamy
-
Aporogamy
-
Chalazogamy
-
Vegetative fertilization
In Casuarina, fertilization takes place through
-
Mesogamy
-
Porogamy
-
Chalazogamy
-
Apogamy
In ovule, exostome is
-
Area just outside the micropyle
-
Area at the tip of nucellus
-
Part of micropyle enclosed by inner integument
-
Part of micropyle enclosed by outer integument
In an ovule, an opening is formed at the tip of ovule by the integuments called as micropyle. The micropyle acts as a pore for the entry of pollen tube into the ovule for fertilization. In bitegmic ovules, the opening is formed by the inner integument and is called endostome. If the opening is formed by the outer integument it is called exostome. Sometimes it is formed by both the integuments, then it is called as amphistome.
In Angiosperms pollen tube liberate their male gametes into the : -
-
Central cell
-
Antipodal cells
-
Egg cell
-
Synergids
Which one of the following was observed for the first time by Treub?
-
Entry of pollen tube into the ovule through the micropyle in Casuarina.
-
Entry of pollen tube into the ovule through the chalaza in Casuarina.
-
Entry of pollen tube into the ovule through the integuments in Hibiscus.
-
Entry of pollen tube into the ovule through the chalaza in Hibiscus.
-
Casuarina equisetifolia is a monoecious, wind-pollinated species that undergoes chalazogamy fertilization.
- In this type of fertilization, the pollen tube penetrates the ovule through the tissue of the chalaza.
- It was first observed by Treub in 1981 in Casuarina species.
Number of male gemetes present in pollen tube are
-
1
-
2
-
3
-
4
The pollen tube consists of two male gametes. One male gamete fertilizes the egg cell placed in between the egg apparatus and forms the diploid oospore/zygote which forms embryo after maturation. While the other male gamete fuses with the two polar nuclei of the central cell and forms the triploid PEN (Primary Endosperm Nucleus) which results in the formation of endosperm after maturation.
During fertilization male gametes are carried by pollen tube. This is called ________.
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Syngamy
-
Mesogamy
-
Polygamy
-
Siphonogamy
Growth of pollen tube towards embryo sac is
-
Geotropism
-
Chemotaxis
-
Phototaxis
-
Thigmotaxis
Chemotaxis is the movement of an organism or plant in response to a chemical stimulus. Somatic cells, bacteria and other single cell or multicellular organisms direct their movements according to certain chemicals in their environment. It is clearly seen in the case of growth of pollen tube towards the embryo sac. The pollen tube does not directly reach the ovary in a straight line. It travels near the skin of the style and curls to the bottom of the ovary, then near the receptacle, it breaks through the ovule through the micropyle and the pollen tube bursts into the embryo sac.
If the integuments are pierced by the pollen tube during fertilization.
-
Porogamy
-
Mesogamy
-
Chalazogamy
-
Siphonogamy
In mesogamy, pollen tube enters the ovule through the integuments or funiculus. After the pollen tube enters the embryo sac, its apex dissolves and the male gametes are liberated. One of the male gametes are liberated. One of the male gametes fuses with the egg and produces a diploid zygote which by further division develops into an embryo. The other male gamete fuses with the diploid secondary nucleus and produces a triploid primary endosperm nucleus. This is called double fertilization.
Chalazogamy is characteristics of
-
Casuarina
-
Betula
-
Cucurbita
-
Both (A) and (B)
Pollen tube releases sperms in ...
-
Egg cell
-
Antipodals
-
Centre cell
-
Synergids
Synergid cells are two specialized cells that lie adjacent to the egg cell in the female gametophyte of angiosperms and play an essential role in pollen tube guidance and function. The term synergid comes from the Greek word ' Synergos' which means 'working together' and was reportedly coined by Eduard Strasburger. The pollen tube grows towards and into one of the synergid cells, which begins to degenerate as the pollen tube enters it. The pollen tube then ceases growth, ruptures and releases its two sperm cells which migrate to the egg and central cell, fertilization of which gives rise to the embryo and endosperm, respectively. The synergid cells are necessary for pollen tube guidance in the ovule.
Movement of pollen tube is
-
Chemotropism
-
Hydrotropism
-
Phototropism
-
None of the above
Paratonic growth movements are the induced movements of growth, caused by external stimuli, such as gravity, light, water or contact. The movements show a directional relation to the stimulus. The stimuli are effective in causing growth movements only when they are unidirectional. Such movements are generally known as tropic movements and the phenomenon is referred to as tropism.
(A) Geotropism
(B) Phototropism
(C) Hydrotropism
(D) Chemotropism
(E) Thigmotropism
In flowering plants growth of pollen tube towards embryo sac is an example of chemotropism and occurs in response to chemicals secreted by synergids in embryo sac.
Movement of male gametes in lower plants (fern, bryophytes) is
-
Thermotactic
-
Chemotropism
-
Chemotactic
-
Phototactic
Movements of locomotion are generally very fast movements, which may be
(A) Autonomic or spontaneous and
(B) induced or paratonic.
The induced locomotory movements are also called as tactic movements induced by external stimuli. Based on the nature of stimuli, these may be of three types:
(i) Phototactic movement: Seen in zoospores and gametes, which are provided with a light sensitive eye spot, which is attracted by low light intensities.
(ii) Thermotactic movement: Movement in response to heat stimulus is seen in certain motile algae, like Chlamydomonas, which moves from a colder to a warmer place.
(iii) Chemotactic movement: In bryophytes and pteridophytes, the swimming antherozoids are attracted towards the archegonium by chemical stimuli, such as organic substances, like sugar, malic acid and so on.
The movement of pollen tube is called as
-
Chemotropism
-
Thermotaxis
-
Thermonastic
-
Hydrotropism
The pollen tube grows towards embryo sac because of influence of certain chemicals. Pollen tube most commonly enters embryo sac through micropyle and bursts in one of the synergid. It is believed that filiform apparatus of synergids secrete pollen tube attracting chemicals. Mineral; boron is required for germination of pollen grains and elongation of pollen tube. The growth of pollen tube is an example of chemotropism.
In a cucumber, pollen tube enters embryo sac through
-
Integuments
-
Micropyle
-
Endosperm
-
Chalaza
- Pollen tube eventually reaches the micropyle of an ovule to enter the embryo sac and for this purpose, it may follow one of the following three routes:
- 1. Porogamy- when the pollen tube enters the ovule through the micropyle. It is common for most of the angiosperms.
- 2. Mesogamy- when the pollen tube enters through the integuments (Cucumber) or through funiculus (Pistacia).
- 3. Chalazogamy- when the pollen tube enters through the chalazal tissues (Casuarina).
- Hence In a cucumber, pollen tube enters embryo sac through Intehuments.
- So, the correct answer is 'Integuments'.
Growth of pollen tube towards embryo sac is termed as
-
Geotropism
-
Chemotaxis
-
Phototaxis
-
Thigmotaxis
Geotropism is movement or growth with respect to gravitation force; it may be positive geotropism (in direction of gravity) or negative geotropism (away from gravity). This makes option A incorrect as growth of pollen tube does not occur in response to gravity. Phototaxis refers to movement/growth of plant or plant part in response to sunlight. This makes option C incorrect as growth of pollen tube occurs towards the embryo sac, not towards or away the sunlight. Thigmotaxis refers to unequal growth caused by contact of plant part with a solid surface which makes option D incorrect. A tropic response of plant or plant part towards a chemical stimulus is referred to as chemotaxis. Pollen tube growth towards the embryo sac is driven by ion flux (reactive oxygen species) and calcium gradient which makes option B correct.
The pollen tube usually enters the embryo sac
-
Between the egg cell and synergid
-
By directly penetrating the egg
-
Between one synergid and antipodal cell
-
By knocking off the antipodal cells
The eight nucleate female gametophytes of flowering plants have an egg apparatus at micropylar end which in turn has one egg cell and two flanking cells. The flanking cells are known as synergids and have finger like projections of wall in their cytoplasm, the filiform apparatus. They serve as site for entry of pollen tube into one of the synergid followed by disintegration of later. The pollen tube pierces through nucellus and traverses the wall of embryo sac between egg and synergid. Filiform apparatus guide the pollen tube to egg nucleus and thereby facilitate syngamy. This makes option A correct. Option B is incorrect as egg nucleus does not have filiform apparatus to guide the direct entry of pollen tube into it. Three cells present at chalazal end of embryo sac are called as antipodals which makes options C and D incorrect as antipodals and synergids are present at opposite ends of embryo sac.
The process of carrying of male gametes near female gametes by pollen tube is known as
-
Porogamy
-
Chalazogamy
-
Siphonogamy
-
Mesogamy
Siphonogamy is the condition in plants in which pollen tubes are developed for the transfer of the male cells to the eggs. The seed plants are termed as siphonogamous. As a consequence, the spermatophytes are called as siphonogamous by some botanists. Syngamy is the fusion of gametes producing in the formation of a zygote, which develops into a new organism.
Porogamy is the entrance of the pollen tube in the seed plants through the micropyle. Whereas Chalazogamy is the process of fertilization in which the pollen tube penetrates to the embryo sac.
Therefore, the correct answer is option C.
Entry of pollen tube into ovule through chalaza was first discovered by Treub in a xerophyte. The plant is associated with a pair of characters(i) Unisexual flowers (ii) Sessile flowers (iii) Centripetal arrangement of flowers (iv) Bisexual flowers. The correct pair is?
-
ii and iii
-
iii and iv
-
ii and iv
-
i and ii
The entry of the pollen tube into the ovule through the chalaza is known as the chalazogamy. This was discovered by Treub. One such example of xerophyte is Casuarina, which is a plant which can withstand prolonged periods of drought. A flower is a bracteate, bracteolate, sessile, incomplete and unisexual.
Thus, the correct option is D.
Movement of pollen tube towards ovule is
-
Chemotropism
-
Haptotropism
-
Thigmotropism
-
Phototropism
Chemotropism is the directional growth movement in response to external chemical stimuli. Movement of pollen tube towards ovule is chemotropic movement. Haptotropism is the growth movement of plant part in response to the touch stimuli. Thigmotropism is the growth movement in response to the touch. Phototropism is the growth movement of plant part in response to the light.
The most common type of tapetum is?
-
Secretary or glandular type
-
Amoeboid or invasive type
-
Nonglandular and noninvasive type
-
Resupinate type
Amoeboid or Invasive is also known as Periplasmodial Tapetum. It is the most common type of tapetum in the angiosperms. This type of tapetum can be seen in Alisma, Butomus, Tradescantia and Typha, etc. The tapetal cells fuse among themselves to make the tapetal periplasmodium. The protoplast of the fused tapetal cells then moves into the locule. This protoplast movement into the locule, may take place during meiotic prophase.
Thus the correct option is B.
Growth of pollen tube is?
-
Apical
-
Basal
-
Intercalary
-
Diffused
After the germination of pollen grains on stigma pollen tube is produced through a germ pore . Pollen tube grows chemotropically through the tissue of stigma and style in response to sugary fluid.
Pollen tube is covered by a membrane made of.
-
Pectocellulose
-
Sporopollenin
-
Cellulose
-
Lignocellulose
Movement of pollen tube towards embryo sac is?
-
Thermotactic
-
Phototactic
-
Chemotactic
-
Thigmotactic
Cells present in mature male gametophyte of angiosperms is?
-
One
-
Two
-
Three
-
Four
Fertilization which involves carrying male gametes by pollen tube is called
-
Porogamy
-
Siphonogamy
-
Chalazogamy
-
Syngonogamy
The process fertilization accomplished by means of pollen tube in which the transfer of male gametes to the female gametes takes place.
In mesogamy, pollen tube enters the ovule through
-
Middle of integuments after piercing the tissues
-
Middle of integuments without piercing the tissues
-
Chalaza
-
Middle of micropyle
Pollen tube discharges its male gametes into.
-
Egg
-
Healthy synergid
-
Degenerating synergid
-
Central cell
Plant part having two generations, one within the other is?
-
Seed
-
Germinated pollen grain
-
Embryo
-
Unfertilized ovule
Entry of pollen tube through chalazal end is
-
Syngamy
-
Porogamy
-
Mesogamy
-
Basigamy
Pollen tube usually enters the embryo sac
-
Through one of the synergids.
-
Directly penetrates the egg.
-
Between one synergid and central cell.
-
By knocking of antipodal cells.
Commonly the pollen tube enters the ovule through
-
Hilum
-
Chalaza
-
Funicle
-
Micropyle
Based on entry of pollen tube into ovule, which one is mesogamy.
-
Through micropyle
-
Entry through funiculus, chalaza and embryo sac from egg apparatus end
-
Through placenta and funiculus
-
Through integument
Normally how many pollen mother cells are necessary for formation of $400$ seeds.
-
$200$
-
$500$
-
$100$
-
$400$
Through which cell of the embryo sac, does the pollen tube enter the embryo sac-
-
Persistant synergid
-
Egg cell
-
Central cell
-
Degenerated synergid
The pollen tube enters the embryo sac through the micropylar end. It can enter directly through the synergid or can enter from between the egg cell and synergid.
The element known to be involved in the polarized growth of pollen tube is?
-
Potassium
-
Magnesium
-
Sodium
-
Calcium
When pollen tube enters through microphyte, the process is called _______________.
-
Porogamy
-
Chalazogamy
-
Mesogamy
-
Apogamy
When a dicot plant is infected by Agrobacterium tumefaciens, the T-DNA in Ti-plasmid induces the plant to produce?
-
Growth hormones like auxins and cytokinins
-
Growth inhibitors like absciscic acid
-
Fatty acids
-
Leghaemoglobin
Agrobacterium tumefaciens is the causal agent of crown gall disease (the formation of tumours). It is a rod-shaped, Gram-negative soil bacterium. The plasmid of this bacterium is called Ti-plasmid, it shows T-DNA. This plasmid used to produce growth hormones like auxins and cytokinins.
So, the correct option is ‘Growth hormones like auxins and cytokinins’.
Length of pollen tube depends on the distance between
-
Pollen grain and upper surface of stigma
-
Pollen grain on upper surface of stigma and ovule
-
Pollen grain in anther and upper surface of stigma
-
Upper surface of stigma and lower part of style
Length of pollen tube depends upon distance of pollen on stigma and ovule because after pollination pollen germinates and form pollen tube that reaches upto ovule in ovary and release male gamete to fuse with female gamete.
Mesogamy is
-
Fusion of similar male and female gametes
-
Fusion of morphologically different but physiologically similar gametes
-
Entry of pollen tube through the integument
-
None of the above
There are various ways by which the pollen tube can reach embryo sac for pollination.
What is the function of the filiform apparatus at the entrance into ovule?
-
Guides pollen tube from synergid to egg
-
Helps in the entry of pollen tube into a synergid
-
Prevents entry of more than one pollen tube into a synergid
-
Brings about opening of the pollen tube
What is the function of filiform apparatus in an angiospermic embryo sac?
-
Guides pollen tube from synergid to egg
-
Helps in the entry of more than one pollen tube into a synergid
-
Prevents entry of more than one pollen tube into a synergid
-
Brings about opening of the pollen tube.
The function of filiform apparatus in an angiospermic embryo sac is to guide the entry of pollen tube from synergid to egg. The synergid cells present within the female gametophyte play a vital role in the reproduction process in angiosperm. The cell wall of synergid develops an extremely thick structure called the filiform apparatus at the micropylar end of the ovule.
The most common type of entry of pollentube into the ovule is
-
Mesogamy
-
Chalazogamyy
-
Basigamy
-
Porogamy
Porogamy is the most common type in which the pollen tube enters the ovule through the micropyle. An example includes lily, etc.
So the correct option is D.
Siphonogamy occurs in
-
Gymnosperms
-
Monocots
-
Dicots
-
All of the above
Growth of the pollen tube is
-
Apical
-
Intercalary
-
Basal
-
Intermittent
In sexual reproduction of plants, the sperm is transferred to the egg through a long, polarized tube of a pollen cell called as the pollen tube. The growth of the pollen tube is apical. It grows at its tip at very rapid rate. The rapid growth is due to a highly polarized fusion of apical vesicles. These transport cell wall components to the growing tip via cytoplasmic streaming and are incorporated into a zone of elongation in the apical region of the pollen tube. Hence, the pollen tube extends its length by apical growth in a relatively small region.
Choose the correct answers from the alternatives given.
Entrance of a pollen tube into an ovule through the micropyle is called
-
porogamy
-
mesogamy
-
chalazogamy
-
apogamy
After reaching ovary, the pollen tube enters the ovule. When the pollen tube enters the ovule through micropyle, it is called porogamy. It is the most common type. e.g., Lily.
Entry of pollen tube in the ovule through integument is called
-
Chalazogamy
-
Basigamy
-
Mesogamy
-
Porogamy
The apical growing region of pollen tube called
-
Growing zone
-
Cap block
-
Non-vacuolate region
-
Organelle region
Apical zone of pollen tube contains abundant vesicles but lacks cell organelles. It is hemisphere in shape and transparent in nature. This transparent apical growing region of pollen tube is called as cap block. It exists only until the tube is growing. It disappears as soon as the growth ceases.
The functional part of the pollen tube is separate from the rest by
-
Vacuoles
-
Callose plugs
-
Septa
-
Both B and C
Callose is a beta-1,3-glucan. It is the major component of the pollen tube cell wall. It is also deposited within the cytoplasm as distinct callose grains. This leads to the formation of callose plugs. Callose plugs separate the living, growing and functional part of the pollen tube in the tip from the remaining degenerating part.
Site of meiosis in angiosperms is
-
Meristem
-
Spore mother cell
-
Roots
-
Petals or pollens
Site of meiosis in Angiosperms is the spore mother cell.
In plants, meiosis can be observed in
-
Root tip
-
Leaf primordia
-
Sporangia
-
Spores
In plants, meiosis can be observed in sporangia. A microsporangium is the part of plant is suitable for the study of meiosis. A typical anther contains four microsporangia. The microsporangia form sacs or locules in the anther. The two separate locules on each side of an anther may fuse into a single locule. Each microsporangium is lined with a nutritive tissue layer called the tapetum and initially contains diploid pollen mother cells. These undergo meiosis to form haploid spores. The spores may remain attached to each other in a tetrad or separate after meiosis.
Which of the following is the site of meiosis in higher plants?
-
Growth cells
-
Root tip cell
-
Stomatal cell
-
Spore mother cell
The site of meiosis in higher plants is the spore mother cell. In land plants and some algae, there is an alternation of generations such that meiosis in the diploid sporophyte generation produces haploid spores. These spores multiply by mitosis, developing into the haploid gametophyte generation, which then gives rise to gametes directly. In both animals and plants, the final stage is for the gametes to fuse, restoring the original number of chromosomes.
In which of the following meiosis takes place?
-
Pollen grains
-
Pollen tube
-
Pollen mother cells
-
Generative cells
Meiosis occurs in microspores mother cells which are diploid cells; to produce microspores or pollen grains. Each microspore mother cell produces four microspores after a meiotic division.
Which part of plant is suitable for the study of meiosis?
-
Root apex
-
Ovary
-
Anther
-
Shoot apex
Anther is the part of plant is suitable for the study of meiosis. A typical anther contains four microsporangia. The microsporangia form sacs or locules in the anther. The two separate locules on each side of an anther may fuse into a single locule. Each microsporangium is lined with a nutritive tissue layer called as the tapetum and initially contains diploid pollen mother cells. These undergo meiosis to form haploid spores. The spores may remain attached to each other in a tetrad or separate after meiosis.
Meiosis is best observed in dividing.
-
Cells of apical meristem
-
Cells of lateral meristem
-
Microspores and anther wall
-
Microsporocytes
In tomato, meiosis occurs in
-
Pollen sac and ovule
-
Microspore and megaspore mother cells
-
Both A and B
-
Zygote
How many meiotic divisions are required to produce $1000$ pollen grains?
-
$200$
-
$250$
-
$500$
-
$1000$
Which one shows meiosis?
-
Root tip
-
Archesporium
-
Pollen grain
-
Anther
Meiotic division occurring just at the time of gametogenesis is
-
Sporic
-
Initial
-
Intermediate
-
Terminal
- In plants, meiosis is occurring as in diploid sporophyte to produce haploid spores.
- The haploid spores are germinating to produce structures called gametophytes. The gametophytes then produce gametes.
- Gametic or the terminal meiosis occurs in all multicellular animals. It takes place in the gonads and hence as results in the formation of gametes.
- It is responsible for gametogenesis and does not give rise to gametophytes.
- The correct option is D.
Development of female gametophyte directly from megaspore mother cell without meiosis is called.
-
Apogamy
-
Apospory
-
Syngamy
-
Parthenospore
Formation of gametophyte directly from sporophyte without meiosis is?
-
Apospory
-
Apogamy
-
Parthenogenesis
-
Amphimixis
Read the given statements.
(i) The outer exine is made up of sporopollenin.
(ii) Inner intine is pecto-cellulosic in nature.
(iii) Generative cell is bigger and contains abundant food reserve.
(iv) Vegetative cell is small and floats in the cytoplasm of the generative cell.
-
(i) and (ii)
-
(ii) and (iii)
-
(iii) and (iv)
-
(i) and (iv)
In a mature pollen grain, the generative cell is smaller and the tube(or vegetative) cell is larger. In the later stages of development of pollen grain, callose dissolves and the naked generative cell comes to lie freely in the cytoplasm of the tube cell. The tube cell has a cytoplasm that is rich in the food reserve (starch, protein, fat with mostly unsaturated fatty acids).
Sporic meiosis occurs in
-
Animals
-
Thallophyta
-
Bryophyta
-
All plants except thallophyta
Sporic meiosis, has mitosis in two stages, both the diploid and haploid stages, termed diplobiontic.
$32$ chromosomes are present in the green leaf of Onion. When meiosis takes place to produce gametes after fertilization how many chromosomes will be there in triploid nucleus.
-
$32$
-
$16$
-
$48$
-
$9$