Gymnosperms Plant King. Flashcards

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1
Q

What does ‘gymnosperm’ mean?

A

‘Gymnosperm’ means ‘naked seeds.’ It refers to plants where the ovules and seeds are not enclosed by an ovary wall and remain exposed.

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2
Q

What are the types of plants included in gymnosperms?

A

Gymnosperms include medium-sized trees, tall trees, and shrubs. An example is the giant redwood tree Sequoia, one of the tallest tree species.

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3
Q

What type of roots do gymnosperms have?

A

Gymnosperms have tap roots. Some, like Pinus, have fungal associations (mycorrhiza), while others, like Cycas, have coralloid roots associated with nitrogen-fixing cyanobacteria.

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4
Q

How do stems differ in gymnosperms?

A

Stems in gymnosperms can be unbranched (Cycas) or branched (Pinus, Cedrus).

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5
Q

How are the leaves of gymnosperms adapted to their environment?

A

Gymnosperm leaves are adapted to withstand extreme temperatures, humidity, and wind. For example, conifers have needle-like leaves with a thick cuticle and sunken stomata to reduce water loss.

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6
Q

What type of spores do gymnosperms produce?

A

Gymnosperms are heterosporous (micro and macrospores), producing haploid microspores and megaspores.

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7
Q

What are strobili in gymnosperms?

A

Strobili (cones) are structures where sporophylls bearing sporangia are arranged spirally. Male cones are called microsporangiate, and female cones are called macrosporangiate.

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8
Q

How does the male gametophyte develop in gymnosperms?

A

The male gametophyte develops from microspores within the microsporangia, forming a pollen grain. It is highly reduced and limited to a few cells.

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9
Q

What is the female gametophyte’s development process in gymnosperms?

A

The megaspore mother cell undergoes meiosis to form four megaspores. One megaspore develops into a multicellular female gametophyte, which bears archegonia and remains within the megasporangium.

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10
Q

How does fertilization occur in gymnosperms?

A

Pollen grains are released, carried by air currents, and come in contact with ovules. The pollen tube grows toward the archegonia, discharges male gametes, and fertilization occurs.

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11
Q

How are seeds formed in gymnosperms?

A

After fertilization, the zygote develops into an embryo, and the ovules develop into seeds. These seeds remain naked (uncovered).

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12
Q

How do gymnosperms differ from bryophytes and pteridophytes?

A

In gymnosperms, the male and female gametophytes are not free-living. They remain within the sporangia on the sporophyte.

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