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.

1. Algae such as Ectocarpus and Polysiphonia represent haplo-diplontic life cycle’ pattern.
2. Algae such as Fucus and Sargassum represent diplontic life cycle-pattern.

1. Selaginella.
2. Sphenopsida.

Sporophyte.

Gymnosperms.

Lycopodium.

1. Integuments.
2. Secondary nucleus.

Cycas have coralloid root in which nitrogen-fixing cyanobacteria is present.

Pinus gerardiana (chilgoza).

In bryophytes male and female sex organs are called antheridia and archegonia.

1. Algae.

Algae.

In monocots stems vascular tissues are scattered, while in dicot they are arranged around the central axis.

Pteridophytes.

Sargassum.

Zygote.

Floridean Starch.

Haplontic life cycle-Volvox, Spirogyra and some species of Chlamydomonas.

Zostera.

Meiosis occurs during spore formation.

Gelidium, Gracilaria.

Artificial, natural and phylogenetic.

1. Chlorella Chlamydomonas.
2. Spirogyra/ Ulothrix.

Leaf-like appendages are called sporophylls that bear sporangia.

Haplontic life cycle shows zygotic meiosis.

Since the endosperm is formed by triple fusion (two polar nuclei fuse to form a secondary nucleus, which fuses with a male gamete), it is triploid.

Female gametophyte has one oospore or egg and two helping cells or synergids for attracting the pollen tube.

Gemma cup.

Starch.

On the megasporophylls in a female strobilus/ cone.

Types of venation found in plants are:

1. Dicots Reticulate venation.
2. Monocots Parallel venation.

Cycads (members of class-Cycadopsida of gymnosperms).

Marchantia.

The vascular plants dominate earth and made the planet green everywhere. The features which enable this quality to happen are:

1. Strong roots capable of penetrating deep into the soil.
2. Development of waterproof layer on aerial surfaces especially the leaves to reduce transpiration.
3. Presence of strong, woody mechanical tissue to provide mechanical support to aerial parts and allow them to rise to a great height.
4. Vascular tissues are present for long distance transport of substances.

Flower.

Conifer needles fall down and cover the soil and absorb rain water.

Since the embryo sac develops from a megaspore formed after meiosis, it is haploid.

The endosperm provides nourishment to the developing embryo.

It is obtained from Ephedra, a gymnosperm. Ephedrine is used in curing respiratory diseases in humans.

Pteridophytes also need water for fertilisation like bryophytes.

Mosses, along with lichens are the first organism to colonise rocks, hence are ecologically important to develop an ecosystem in bare places.

Because they are red in colour due to the predominance of the red pigment, r-phycoerythrin.

Mosses grow in moist, shaded areas in hills and foot hills.

1. Wolffia.
2. Eucalyplus.

Selaginella and Equisetum.

Mosses.

Pinus.

Haplo-diplontic life cycle-Bryophyfes and Pteridophytes.

Bryophytes are classified into two groups. That are liverworts and mosses.

Alternation of generations is regular switch over from gamete bearing haploid gametophyte to haploid spore producing diploid sporophyte.

A small orchid lives underground. It has mycorrhizal association which helps it in obtaining nourishment from decaying organic matter.

After falling from tree they cover the soil and absorb rain water and prevent soil from getting evoded.

The cell walls are visible in plant cells.

Thalloid.

The two main features of brown algae are:

1. They are multicellular eukaryotic algae.
2. They are fucoxanthin and phycocolloid rich members. e.g., Laminaria and Fucus.

Because a bryophyte lives on land but needs water for reproduction. In other words it needs both land and water to survive.

Since there is no ovary to enclosene ovule(s), there is no fruit to enclose the seed(s); hence they are nakedseeded plants.

By Fragmentation and Gemmae formation.

Starch.

Cycas is a living representative of once a large group of gymnosperms which has became largely extinct.

Natural system of classification is based on morphology, anatomy, cytology, embryology, molecular biology and genetics of organisms.

Fruit develops from the whole ovary of a pistil.

Chlorella.

Phylogenetic system of classification.

Flowering plants are placed in ascending series related to their complexity of floral morphology.