Overview
👉Gymnosperms evolved from Pteridophyte. As they are seed bearing plants but their seeds are naked because the ovule are not enclosed by an ovary wall and remain exposed before and after the fertilization.
👉They have vascular tissue for transportation of food and water, their plant body is divided into roots, stems and leaves but they do not bear flowers.
👉The term gymnosperm signifies the naked seed because their ovule is not covered by an ovary wall.
👉Gymnosperms are grouped under the embryophyta. They are like shrubs , medium height plants and some are long trees.
👉Sequoia is one of the tallest trees of gymnosperm, called as giant redwood gymnosperm.
👉Gymnosperms can tolerate moist or dry conditions. Gymnosperms evolved in the Triassic period. Approx 1200 species have been recognized under the gymnosperm.
👌👌Remember -Gymnosperms are classified into four types -Cycadophyta, Ginkgophyta, Gnetophyta and coniferophyta.
🌑General characters of Gymnosperms
🌑Habitat -
🔴They are found in colder regions and They develop needle-like leaves to reduce surface area.
🔴In addition to this, the leaves of gymnosperm are well adapted to withstand adverse conditions like temperature , humidity etc.
🔴They also have thick cuticles and sunken stomata to reduce the loss of water.
🌑Symbiotic association
🔴Some gymnosperms have fungal symbiotic association in their roots.
🔴In Pinus, fungus make association in the root of pinus. This association is called mycorrhiza.
🔴In cycas, nitrogen fixing cyanobacteria like Nostoc make association in the root of cycas. Such roots are special in structure termed Coralloid roots.
🌑Morphological feature
🔴The roots in gymnosperm are tap roots because the primary branch of the root has various branches.
🔴The leaves may be simple or compound.
🔴The stem is branched like in Pinus or unbranched like in cycas.
🌑Microsporophyll and Megasporophyll
🔴The gymnosperm has a group of two kinds of leaves called sporophyll.
🔴These sporophyll bear sporangia that also produced two kinds of spores - microspore and megaspore.
🔴In gymnosperm, small leaves are arranged in the form of microsporophyll which bear microsporangia and produce microspore.
🔴The bunch of small leaves in gymnosperm is called female strobili or female cone.
🔴Similarly, Large leaves are arranged in the form of megasporophyll which bear megasporangia and produce megaspore.
🔴The bunch of large leaves in gymnosperm is called male strobili or male cone.
🔴In Pinus, Male and female cones are found in a single plant whereas in Cycles male and female cones are present at different plants.
🌑Reproductive structure
🔴At microsporophyll, inside the microsporangia, microspores divide and produce male gametophyte or pollen grains.
🔴On the other hand, At megasporophyll, inside the megasporangium, an ovule is present and it is surrounded by the protective envelope called integuments. The cells of integuments are called nucellus.
🔴A single cell of nucellus is differentiated and forms a megaspore mother cell.
🔴These megaspore mother cells divide by meiosis and form four megaspore.
🔴Out of four megaspore , one megaspore develops into a female gametophyte. This female gametophyte contains one or two archegonia bearing eggs.
🌑Reproduction
🔴In gymnosperm, male gametophyte and female gametophyte are retained within microsporangia and megasporangia respectively.
🔴Pollen grains are carried by the wind and reach the ovule.
🔴At the ovule, pollen grain germinates the pollen tube and discharges male gamete at the mouth of Archegonia.
🔴As a result, fertilization occurs by the fusion of male gamete of pollen grains and egg of archegonia.
🔴After fertilization, zygote is changed into embryo and ovule into seed that is without covering. Example-Cycas,Pinus,Ginkgo, Thuja, Cedrus,Picea etc.
1. In which group of plants, the ovule are not enclosed by an ovary wall and remain exposed before and after the fertilization.
A. Bryophytes
B. Pteridophytes
C. Gymnosperms
D. Angiosperms
Answer : C
2. Which of the following statement is Incorrect.
A. Only Compound leaves are found in Gymnosperm.
B. Tap root are present in Gymnosperms.
C. The leaves of Gymnosperms are well adapted to withstand against temprature, humidity, and wind.
D. Gymnosperms include medium size tree or tall tree and shrub.
Answer: A
3. How many statement are correct.
1. In Gymnosperms, the seed that form after the fertilization, are naked.
2. The leaves may be simple or compound.
3. In conifers, leaves are pointed or needle like to reduce the surface area.
4. The thick cuticle and sunken stomata help to reduce the water loss.
5. Gymnosperms generally have fibrous root system.
A. Two B. Three
C. Four D. Five
Answer : C
4. Which one of the following is giant, redwood tallest Gymnosperms.
A. Sequoia
B. Ginkgo
C. Cedrus
D. None of the above.
Answer : A
5. Consider the following statement and select the correct code.
1. Root of Pinus has fungal association in form of Mycorrhiza.
2. Root of Cycas is Coralloid root because it has symbiotic association with nitrogen fixing Cyanobacteria.
A. Only 1 B. Only 2
C.Both 1 and 2
D. Neither 1 nor 2
Answer : C
6. Which one of the following statement is not correct about the Cycas, a Gymnosperms.
A. Male cone and female cone are borne on different tree.
B. Stem is unbranched.
C. The pinnately leaves persist for a fer years.
D. Roots are Coralloid because Roots have association with nitrogen fixing Cyanobacteria.
Answer : B
7. Which of the following statement is Incorrect with respect to Gymnosperm.
A. They are heterosporous and produce microspore and megaspore with in sporangia.
B. Sporangia are borne on sporophyll which are arranged in form of cone or strobli.
C. Microsporangiate is male cone which bear micosporophyll and microsporangia.
D. Macrosporangiate is female cone which bear megasporophyll and megasporangia without the ovule.
Answer : D
8. Consider the following term and arrange them in order.
1. Sporophyll
2. Cone
3. Sporangia
4. Spore
A. 2 - 1 - 3 - 4
B. 1- 3 - 2 - 4
C. 2 - 1 - 4 - 3
D. 2 - 1 - 3 - 4
Answer: A
9. Which of the following statement is correct about the pollen grain or microspore of Gymnosperm.
A. Pollen grains are highly reduced male gametophyte with limited number of cells.
B. Microspore are formed with in microsporangia on male cone.
C. Microspore are developed into male gametophyte.
D. All of the above
Answer : D
10. The stem is branched in
A. Pinus and Cedrus
B. Cycas and Cedrus
C. Cycas and Pinus
D. Cycas, Pinus, Cedrus.
Answer : A
11. Consider the following statement with respect to the ovule of Gymnosperm and select the correct code:
1. Ovule or megasporangi are born on mega sporophyll.
2. Ovule is composed of cells of nucellus which is protected by envelop.
3. Ovule may be clustered in form of female cone.
4. One of the cell of nucellus is differentiated and act as megaspore mother cell.
A. 1 and 4.
B. 2, 3 and 4
C. 1, 3 and 4
D. 1, 2, 3 and 4
Answer : D
12. In Gymnosperm, Mega spore mother cell which is diffrentiated from nucellus divide by meiosis and form
A. One megaspore
B. Two megaspore
C.Three megaspore
D. Four megaspore.
Answer : D
13. Out of four megaspore, one megaspore is developed into multicellular gametophyte which bear
A. One archegonium
B. Two archegonia
C. Three archegonia
D. Two or MORE archegonia.
Answer: D
14. How many statement is / are not correct.
1. Main plant body of Gymnosperm is sporophyte and homosporous.
2. Pollen grain are reduced male gametophyte with limited cell.
3. Female gametophyte is multicellular and retained within megasporangium
4. Male and female gametophyte are not independent and free living.
A. One B. Two
C. Three D. Four
Answer: A
15. Pollen grain are released from microsporangia and reach at mouth of ovule by
A. Water
B . Insect
C. Wind
D. Insect
Answer : C
16. Pollen grains are germinated in form of pollen tube at
A . Archegonia
B. Megasporophyll
C. Ovule
D. Female cone
Answer: C
17. Which of the following event does not occur in archegonia of Gynosperm.
A. Pollen tube discharge male gamete near mouth of archegonia.
B. Fertilisation takes place in archegonia and zygote is formed.
C. Zygote is developed in to embryo inside the archegonia.
D. Ovule is developed into naked seed.
Answer : D
18.Consider the following statement and select the correct code:
1. The male and female cone are borne on same tree in cycas.
2. The male and female cone are borne on different tree in Pinus.
A. Only 1
B.Only 2
C. Both 1 and 2
D. Neither 1 nor 2
Answer : D
19. Identify the following diagram and select the option:
B.Pinus
C.Cycas
D. Ginkgo
Answer: D
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