Biology 1 Marks Question

Isogamy: It is a type of sexual reproduction involving the fusion of morphologically-similar gametes. This means that the gametes are of the same size, but perform different functions. This type of reproduction is commonly observed in Spirogyra.

Archegonium: It is the female sex organ present in bryophytes, pteridophytes, and gymnosperms. In bryophytes and pteridophytes, it generally has a swollen venter and a tubular neck, and contains the female gamete called the egg.

	Homosporous pteridophytes	Heterosporous pteridophytes
1.	They bear spores that are of the same type.	They bear two kinds of spores – microspores and megaspores.
2.	They produce bisexual gametophytes.	They produce unisexual gametophytes.

Reduction divisions in the life cycle of a liverwort, a moss, a fern and a gymnosperm take place during the production of spores from spore mother cells. In case of an angiosperm, the reduction division occurs during pollen grain formation from anthers and during production of embryo sac from ovule.

Antheridium: It is the male sex organ present in bryophytes and pteridophytes and is surrounded by a jacket of sterile cells. It encloses the sperm mother cells, which give rise to the male gametes.

Sporophyll: In pteridophytes, the sporophytic plant body bears sporangia. These sporangia are subtended by leaf-like appendages known as sporophylls. In gymnosperms, microsporophylls and megasporophylls are found. These bear microspores and megaspores respectively.

Protonema: It is the first stage in the life cycle of a moss, developing directly from the spore. It consists of creeping, green, branched, and often filamentous structures.

	Syngamy	Triple fusion
1.	It is the process of fusion of the male gamete with the egg in an angiosperm.	It is the process of fusion of the male gamete with the diploid secondary nucleus in an angiosperm.
2.	A diploid zygote is formed as a result of syngamy.	A triploid primary endosperm is formed as a result of triple fusion.

Diplontic: It is the term used for the life cycles of seed-bearing plants (gymnosperms and angiosperms). In these plants, the diploid sporophyte is dominant, photosynthetic, and independent. The gametophyte is represented by a single-celled (or a few-celled) structure.

It is due to pigments chlorophyll-a and b.

Seeds in gymnosperms are naked, i.e., without ovary wall.

Kingdom-Plantae includes unicellular members of green algae e.g. Chlamydomonas, Chlorella How are algae classified in Whittaker'sclassification?

Algin.

Chlorophyll a and b.

This system is based on common characters of group of organisms, so it can give more or detailed information about the groups of organisms.

The occurrence of two types of fertilisation in the same embryo sac is called double fertilisation that occurs in angiosperms.

Sporophytic phase.

The development to the zygotes into young embryo takes place within the female gametophytes is considered as precursor of seed habit.

Marchantia.

Reticulate Venation.

Parallel Venation.

Dicot angiosperms show secondary growth in their stems and roots.

Engler and Prantl (1887-1899).

Funaria is having both gametophytic and sporophytic generation on the same plant.

Seeds lie naked or exposed on the surface of megasporophyll.

Mosses form dense mat over the surface of ground, thereby helping in preventing soil erosion.

Green algae belong to class-Chlorophyceae, e.g., Chlorella and Spirogyra.

1. Pinus.
2. Cycas.

Liverworts and Mosses.

Coralloid roots of Cycas harbour symbiotic cyanobacteria, which can fix atmospheric nitrogen.

It indicates the possible origin of different organisms.

r-phycoerythrin.

Seeds in gymnosperms remain exposed over the surface of the megasporophylls. This is because megasporophylls are not folded to form pistils like in angiosperms.

The members of Phaeophyceae (brown algae) store mannitol as a reserve food material.

Meiosis occurs during spore formation in a diplontic life cycle.

Equisetum stems.

1. Laminarin.
2. Mannitol.

Pyrenoids; they are located in the chloroplasts.

George Bentham and Joseph Dalton Hooker.

The artificial system of classification was based only on gross morphological characters like habit, colour, number, shape of leaves, etc.

The basic assumption behind phylogenetic classification is organism belonging to the same taxa have a common ancestor.

Flowering plants help pollinators to attract towards them by their flower colour and nectar smell.

Selaginella, Equisetum.

Generative cell divides to form two male gametes.

Syngamy represents generative fertilization Triple fusion represents vegetative fertilisation.

1. r-phycoerythrin.
2. Fucoxanthin.

Because they need water for the transport of male gametes to the female gametes for fertilisation.

It is due to the predominance of pigments chlorophyll a and b.

In lower plants like bryophytes, there are root like structures called rhizoids. These help the lower plants in absorption of water and minerals from the substrate.

Cytotaxonomy is a method of classification. It is based on cytological structures and their relatedness.