Bryophytes - 2

Bryophytes: Dictionary meaning — a group of non-vascular plants that includes mosses and liverworts.
Explanation — The sex organs of bryophytes are multicellular and are specialised structures that produce the male and female gametes.

Sex organs: Dictionary meaning — reproductive structures that produce or contain the gametes involved in sexual reproduction.
Explanation — In bryophytes, the male sex organ is called the antheridium and the female sex organ is called the archegonium.

Multicellular: Dictionary meaning — consisting of many cells.
Explanation — Unlike the reproductive structures of many simpler organisms, bryophyte sex organs are composed of multiple cells and have a protective sterile jacket surrounding the reproductive cells.

Antheridium: Dictionary meaning — the male reproductive organ that produces male gametes.
Explanation — The antheridium is a multicellular structure that produces male gametes called antherozoids or spermatozoids.

Archegonium: Dictionary meaning — the female reproductive organ that produces and contains the egg.
Explanation — The archegonium is a multicellular, flask-shaped structure containing a single egg in its swollen basal region.

Given Statement - The sex organs in bryophytes are multicellular.

Bryophytes: Dictionary meaning — a group of non-vascular plants that includes mosses and liverworts.
Explanation — Bryophytes have multicellular sex organs. The male sex organ is called the antheridium, while the female sex organ is called the archegonium.

Antheridium: Dictionary meaning — the multicellular male reproductive organ that produces male gametes.
Explanation — In bryophytes, the antheridium produces numerous male gametes called antherozoids or spermatozoids.

Archegonium: Dictionary meaning — the multicellular female reproductive organ that produces and contains the egg.
Explanation — The archegonium is the female sex organ of bryophytes and contains the female gamete, or egg.

Male gametes: Dictionary meaning — reproductive cells produced by the male sex organ that participate in sexual reproduction.
Explanation — The male gametes produced by the antheridium are motile and require water to reach the female sex organ for fertilisation.

Given Statement - The male sex organ in bryophytes is called antheridium.

Antheridium: Dictionary meaning — the multicellular male sex organ that produces male gametes in bryophytes.
Explanation — The antheridium produces numerous male gametes called antherozoids, which are biflagellate and therefore capable of movement.

Antherozoids: Dictionary meaning — motile male gametes produced by the antheridium of bryophytes.
Explanation — Bryophyte antherozoids possess two flagella that help them move through water towards the archegonium during fertilisation.

Biflagellate: Dictionary meaning — possessing two flagella.
Explanation — The antherozoids of bryophytes are biflagellate, meaning they have two flagella that enable them to swim through a film of water.

Flagella: Dictionary meaning — slender, whip-like structures that help a cell move.
Explanation — The two flagella of antherozoids provide locomotion and are essential because bryophytes require water for the movement of male gametes during fertilisation.

Given Statement - The antheridium of bryophytes produces biflagellate antherozoids.

Archegonium: Dictionary meaning — the multicellular female reproductive organ that produces and contains the female gamete.
Explanation — In bryophytes, the archegonium is a flask-shaped female sex organ that produces and contains a single egg.

Flask-shaped: Dictionary meaning — having a narrow neck and a broader swollen base, resembling a flask.
Explanation — The archegonium has a swollen basal portion called the venter and a narrow elongated neck, giving it its characteristic flask-like shape.

Egg: Dictionary meaning — the non-motile female gamete involved in sexual reproduction.
Explanation — A single egg is produced and retained within the swollen basal part of the archegonium until fertilisation occurs.

Female sex organ: Dictionary meaning — the reproductive structure that produces or contains the female gamete.
Explanation — The archegonium is the female sex organ of bryophytes. It is multicellular and protects the developing egg within its structure.

Given Statement - The female sex organ called archegonium is flask-shaped and produces a single egg.

Antherozoid: Dictionary meaning — a motile male gamete produced by the antheridium in bryophytes.
Explanation — The antherozoid is the male gamete that moves through water and reaches the archegonium, where it fuses with the egg.

Egg: Dictionary meaning — the non-motile female gamete produced and contained within the archegonium.
Explanation — The egg is the female gamete of bryophytes and is retained inside the archegonium until fertilisation occurs.

Fertilisation: Dictionary meaning — the fusion of male and female gametes to form a zygote.
Explanation — In bryophytes, fertilisation occurs when an antherozoid fuses with the egg inside the archegonium, resulting in the formation of a diploid zygote.

Zygote: Dictionary meaning — the diploid cell formed by the fusion of two gametes during sexual reproduction.
Explanation — The zygote formed after fertilisation is the first diploid stage in the bryophyte life cycle and develops into the sporophyte.

Given Statement - An antherozoid fuses with the egg to produce the zygote.

Zygote: Dictionary meaning — the diploid cell formed by the fusion of male and female gametes during fertilisation.
Explanation — In bryophytes, the zygote is diploid and does not undergo reduction division immediately. Instead, it develops further into the diploid sporophyte.

Reduction division: Dictionary meaning — a type of cell division, also called meiosis, in which the chromosome number is reduced by half.
Explanation — Reduction division does not occur immediately after zygote formation in bryophytes. The zygote first develops into the sporophyte, and meiosis occurs later during spore formation.

Sporophyte: Dictionary meaning — the diploid generation of a plant that produces spores.
Explanation — The bryophyte zygote develops into a multicellular diploid sporophyte. The sporophyte remains attached to and nutritionally dependent on the gametophyte.

Meiosis: Dictionary meaning — a specialised type of cell division that reduces the chromosome number by half and produces haploid cells.
Explanation — In bryophytes, meiosis takes place later in the sporophyte during the formation of haploid spores, not immediately after fertilisation.

Given Statement - Zygotes in bryophytes do not undergo reduction division immediately.

Zygote: Dictionary meaning — the diploid cell formed by the fusion of male and female gametes during fertilisation.
Explanation — In bryophytes, the zygote develops through repeated mitotic divisions into a multicellular diploid body called the sporophyte.

Sporophyte: Dictionary meaning — the diploid generation of a plant that produces spores.
Explanation — The bryophyte sporophyte develops from the zygote and remains attached to the gametophyte. It produces haploid spores through meiosis.

Multicellular: Dictionary meaning — consisting of many cells.
Explanation — The zygote undergoes repeated mitotic divisions and develops into a multicellular sporophyte rather than remaining as a single cell.

Diploid: Dictionary meaning — having two sets of chromosomes, represented as 2n.
Explanation — The zygote and the sporophyte that develops from it are diploid because the zygote is formed by the fusion of two haploid gametes.

Given Statement - The zygote of bryophytes develops into a multicellular body called a sporophyte.

Sporophyte: Dictionary meaning — the diploid generation of a plant that develops from the zygote and produces spores.
Explanation — In bryophytes, the sporophyte is not free-living. It remains attached to the photosynthetic gametophyte and depends on it for nourishment.

Gametophyte: Dictionary meaning — the haploid generation of a plant that produces gametes.
Explanation — The gametophyte is the dominant and photosynthetic plant body of bryophytes. It provides nourishment and support to the attached sporophyte.

Photosynthetic: Dictionary meaning — capable of producing organic food using light energy through photosynthesis.
Explanation — The bryophyte gametophyte is photosynthetic and produces food. The sporophyte remains attached to it and derives nourishment from the gametophyte.

Nourishment: Dictionary meaning — the supply of food and nutrients required for growth and development.
Explanation — The sporophyte of bryophytes depends on the gametophyte for its nutritional requirements because it is not an independent, free-living phase.

Given Statement - The sporophyte is not free-living but attached to the photosynthetic gametophyte and derives nourishment from it.

Sporophyte: Dictionary meaning — the diploid generation of a plant that develops from the zygote and produces spores.
Explanation — In bryophytes, the sporophyte is diploid and contains cells that undergo reduction division or meiosis to produce haploid spores.

Reduction division: Dictionary meaning — a type of cell division, also called meiosis, in which the chromosome number is reduced by half.
Explanation — During meiosis in the sporophyte, diploid cells undergo reduction division, resulting in the formation of haploid spores.

Haploid spores: Dictionary meaning — reproductive cells containing a single set of chromosomes.
Explanation — The spores produced through meiosis are haploid. When they germinate, they give rise to the haploid gametophyte generation.

Meiosis: Dictionary meaning — a specialised cell division that reduces the chromosome number by half and produces haploid cells.
Explanation — In bryophytes, meiosis occurs in certain cells of the sporophyte during spore formation and restores the haploid phase of the life cycle.

Given Statement - Some cells of the sporophyte undergo reduction division (meiosis) to produce haploid spores.

Spores: Dictionary meaning — reproductive cells produced by the sporophyte that can develop into a new organism without fusing with another cell.
Explanation — In bryophytes, the spores are haploid and are produced by meiosis in the sporophyte. Under suitable conditions, these spores germinate and develop into the gametophyte.

Gametophyte: Dictionary meaning — the haploid generation of a plant that produces gametes.
Explanation — The gametophyte is the dominant and photosynthetic phase of the bryophyte life cycle. It develops from the haploid spores and later produces the sex organs.

Germination: Dictionary meaning — the process by which a spore or seed begins to grow and develop into a new organism.
Explanation — When bryophyte spores receive suitable conditions such as moisture, they germinate and develop into the haploid gametophytic phase.

Haploid: Dictionary meaning — having a single set of chromosomes, represented as n.
Explanation — The spores produced by meiosis are haploid, and the gametophyte that develops from them is also haploid.

Given Statement - The spores of bryophytes germinate to produce the gametophyte.