Practice Questions

Gymnosperms range from small shrubs to tall trees. In fact, red wood tree is the tallest tree in the world. They are evergreen, perennial and woody trees and are mostly found in California.

Pteridophytes are classified into four classes namely, Psilopsida; Pteropsida; Sphenopsida; and Lycopsida. Sporopsida doesn’t belong to this set of classification. Therefore, it is the odd among the four.

Sporophyte is dominant phase in the life cycle of a Pteridophyte whereas Gametophyte, Prothallus and Zygote are intermediary stages in the life cycle of a Pteridophyte.

Pteridophytes follow cryptogamae i.e. reproduce spores. The main plant body in Pteridophytes is Sporophyte. Pteridophytes grow in a damp shady area and sometimes even in sandy soils. Pteridophytes have specialized vascular tissues.

Pteridophytes follow cryptogamae i.e. reproduce spores

The main plant body in Pteridophytes is Sporophyte

Pteridophytes grow in dry and cold places like mountains

Pteridophytes have specialized vascular tissues

Equisetum belongs to Pteridophytes under the sub-classification of Sphenopsida. Equisetum is also called as horse’s tail plant because Equus in Latin means horse whereas seta means “bristle”. Equisetum is known to be used as medicine traditionally.

Gametophyte is small and multi-cellular photosynthetic thallus. Sporophyte is also called Pro-thallus. In mosses, gametophyte is the dominant phase. Equisetum and Selaginella have a distinct cone like structure called strobili.

Gametophyte is small and multi-cellular photosynthetic thallus.

In mosses, gametophyte is the dominant phase

Equisetum and Selaginella have a distinct cone like structure called strobili

Sporophytes bear sporangia in leaf like structures called sporophylls. Sporangia further ruptures to form spores that germinate into a gametophyte containing archegonium and antheridium.

Pteridophytes are the first ever evolved plants with vascular tissue in them i.e. they contain xylem and phloem. As they contain vascular tissues, they are capable of growing several meters tall.

Gametes are produced in sex organs called gametophytes. Male gametes are transported to female gametes through water. Male and female gametes further fuse to form a zygotic structure that develops into an embryo. This embryo further develops to form a haploidic structure called sporophytes that bear spores.

Gametes are produced in sex organs called gametophytes

Male gametes are transported to female gametes through water

Male and female gametes further fuse to form a zygotic structure that develops into an embryo

This embryo further develops to form a haploidic structure called sporophytes that bear spores

In mosses, spores germinate to form protonema, a green creepy structure that further develops into leaf like thallus. Rhizoids hold mosses to ground and prevent soil erosion. Gemmae are asexual propagative organs in Liverworts that contain gemmae which further gives rise to a new individual. Water is extremely important for carrying male gamete towards female gamete in order to facilitate sexual reproduction of bryophytes.

In mosses, spores germinate to form protonema, a green creepy structure that further develops into leaf like thallus

Rhizoids hold mosses to ground and prevent soil erosion

Gemmae are sexual propagative organs in Liverworts that contain gemmae which further gives rise to a new individual

Water is extremely important for the sexual reproduction of bryophytes

Zygote is formed by fusion of male and female gametes and is diploid in nature. Zygote doesn’t undergo reduction division immediately after fusion. They instead form a structure called as sporophyte. Sporophyte undergoes meiosis to produce spores. Spores germinate to form new thallus.

Zygote is formed by fusion of male and female gametes and is diploid in nature

Zygote undergoes reduction division to form a structure called sporophyte

Sporophyte undergoes meiosis to produce spores

Haploid gametophyte is the dominant phase in the life cycle of liverworts. Diploid sporophyte, diploid zygote and diploid spores are short living intermediary structures that finally result in gametophyte.

Sporophyte contains mainly of three parts capsule, seta and foot. Capsule is the portion of sporophyte that bears spores and seta is the part that transfers water and nutrients from gametophyte to capsule.

Most of the leafy liverworts resemble mosses in their structure. Leafy liverworts contain oil bodies that are absent in mosses. Leafy liverworts contain lobes in their leaves whereas don’t mosses. In mosses, leaves are spirally arranged but in leafy liverworts leaves grow in two or three rows.

Most of the leafy liverworts resemble mosses in their structure

Liverworts contain oil bodies that are absent in mosses

Moses contain lobes in their leaves whereas leafy liverworts don’t

In mosses, leaves are spirally arranged but in leafy liverworts leaves grow in two or three rows

Bryophytes hold soil firmly and therefore prevent soil erosion. Bryophytes decompose barren rocks and make soil fertile. Bryophytes are used as packing materials and as good fuel. Bryophytes are good absorbers of water and can’t be used for packing of food materials.

Bryophytes decompose rocks and make soil fertile

Bryophytes are used in packing materials and are also good fuel

Bryophytes don’t absorb water and are used to pack food materials

Bryophytes are called as plant amphibians. Although they can manage to grow on land in normal conditions, water is essential for them to transmit male gametes to female gamete in order to facilitate reproduction.

Because they grow in water during summer and on land in winter

Because they grow on land but water is necessary for them to reproduce

Because they grow in water during first half of the year and on land in the second half of the year

Because they grow in water in north part of world and on land in southern part of the world

Sphagnum belongs to bryophytes and to the sub-classification of mosses. Sphagnum has a very good commercial importance and is used in the packing of cookery and glass materials.

In fragmentation, leaves/stems fall off accidentally and grow to form new individuals. Budding is a process in which an outgrowth develops and splits from the parent thallus to produce new individual. Gemmae are tiny, multi-cellular structures that can detach from the parent plant and grow into a new individual. Sporophyte develops from a developed embryo and results in the formation of spores. Sporophyte formation is a sexual process that involves two gametes and hence it is not an asexual process.

The female sex organs in bryophytes are called archegonium and they produce female gamete called egg. The male sex organ is called antheridium and produce male gametes called antherozoids.

Bryophytes are sub-classified into liverworts and mosses. Bryophytes are mostly found in moist hilly areas. Bryophytes don’t contain vascular tissues to transmit water and therefore don’t grow tall. Bryophytes follow cryptogamae.

Bryophytes are sub-classified into liverworts and mosses

Bryophytes are mostly found in dry hilly areas

Bryophytes don’t contain vascular tissues to transmit water and therefore don’t grow tall

Bryophytes are erect with hair like structures called rhizoids. Rhizoids anchor bryophytes to the soil and help in transfer of nutrients from soil to the thallus. They are also called virtual roots of bryophytes.

Phycoerythrin and phycocyanin are biloproteins present in Rhodophycophyta. They are also present in cryptomonads.

Chlorophyll d is present only in the members of Rhodophycophyta. There are five chlorophylls a, b, c, d, e which are found in different organisms.

Phaeophycophyta or the brown algae consists of two lateral flagella. Dinoflagellate or cryptomonads also consists of two lateral flagella.

Bacillariophycophyta or diatoms produce shells (cell walls) containing silica, some of which are very beautiful. Shells of diatoms are called frustules.

The xanthophye walls are typically of cellulose and pectin. The cellular storage product is an oil or (a branched glucan) chrysolaminarin.

Rhodophycophyta reproduces sexually heterogamously by the union of well-differentiated nonmotile male and female germ cells, the spermatia and carpogonia (female sex organs), respectively.

Brown algae are structurally quite complex and kelps belong to this group. Kelps are large, the individual plants reaching a length of several hundred feet.

The chloroplasts of green algae often contain dense regions called pyrenoids, on which surface starch granules are formed.

Volvox is a colonial green alga which may form water blooms. Its colonies are visible to the naked eye.

Sexual reproduction occurs in many species of Chlamydomonas, by isogamy, heterogamy, or oogamy in which isogamy is by far the most common. The zygote divides to form four or eight motile haploid cells are released.

Chladophora is a filamentous branched algal. Chladophora is also called river weed in some areas. It is edible. There are many different varieties of chladophora that are difficult to be classified. Ulva are also called as sea lettuce since they are used in salads.

Chladophora is a filamentous branched algal

Chladophora is also called river weed in some areas

There are many different varieties of chladophora that are difficult to be classified

Spirogyra contains two cellular layers. The outer cellular layer is made of Pectin. The inner cellular in spirogyra is made up of Cellulose. This double cellular layered structure helps them to withstand osmotic pressure.

Plants are classified as Thallophyta and others based on their well differentiable structure. Plants whose structure can’t be differentiated are put under the category of “Thallophyta”.

plants that don’t have well-differentiable structure

The vegetative cells in Phaecophyceae are made up of two layers with the inner one being made of cellulose and the other being made of gelatinous coating of algin. A leaf like photosynthetic organ in Phaecophyceae is called as frond. They also have a stalk called stipe and a substratum called as holdfast.

In Phaecophyceae, food is stored in the form of complex carbohydrates like laminol and manitol. Sometimes food is also stored as oil droplets in phaecophyceae.

Gelidium and Gracilaria is used in the formation of Agar. Agar is used in the preparation of ice-creams and jellies. Apart from the preparation of ice-creams, agar has different uses in both industries and in research.

Multiple fission is a process through which many individuals are produced by repeated nuclear division. Multiple fission takes place under unfavourable conditions. During multiple fission, an outer layer called cyst is formed. Nucleus divides repeatedly and new individuals are formed inside the cyst after which cyst breaks to release new individuals.

Multiple fission is a process through which many individuals are produced by repeated nuclear division

Multiple fission takes place under suitable conditions

During multiple fission, an outer layer called cyst is formed

Nucleus divides repeatedly and new individuals are formed inside the cyst after which cyst breaks to release new individuals

During unfavourable conditions, an outer layer that is formed outside chlamydomonas is called cyst. These unfavourable conditions allow multiple fission inside the cyst.

In fragmentation, a parent organism breaks into a fragment and each fragment gives a new individual. Spirogyra uses fragmentation to reproduction.

In chlorophyceae, chloroplasts contain storage bodies called Pyrenoids. Pyrenoids consists of proteins and starch. Chlorophyceae sometimes store food as oil droplets.

Algae help in increasing oxygen levels in the environment. Chlorella and Spirullina are multi-cellular algae that are rich proteins and are used as food supplements for space travelers. Chlorophyceae comprise algae that contain chlorophyll a and chlorophyll b. Chlorophyceae store food as proteins, starch or as oil droplets.

Algae help in increasing oxygen levels in the environment

Chlorella and Spirullina are multi-cellular algae that are rich proteins and are used as food

Chlorophyceae comprise algae that contain chlorophyll a and chlorophyll b

Chlorophyceae store food as proteins, starch or as oil droplets

In oogamous mode of reproduction, the larger gamete is non-motile and smaller gamete is motile. In humans, sperms being the smaller gamete are motile and the egg being the larger gamete is non-motile. Therefore, reproduction in humans is an example of oogamous reproduction.

Most of the algae reproduce using spore formation. Asexual spores are called as zoo-spores and the reproductive part in algae is called zoosporangium. Under favourable conditions, these organisms germinate to form new organism. Zoo-spores are motile and flagellated.

Most of the algae reproduce using spore formation

Asexual spores are called as zoo-spores and the reproductive part in algae is called zoosporangium

Under favourable conditions, these organisms germinate to form new organism

Zoo-spores are non-motile and flagellated

Volvox grows in colonies. The structures that connect them are called cytoplasmic bridges. Daughter colonies of volvox grow inside the parent colony. They contain flagellum that facilitates their movement.

The structure that connects them are called cytoplasmic bridges

Daughter colonies of volvox grow inside the parent colony

They are immobile due to absence of flagellum

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