Biology

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Life Span of Vegetative Morphology and its Various Types

Based on life span plants are classified into 3 types. They are annuals, biennials and perennials

I. Annuals

A plant that completes its life cycle in one growing season. Example: Maize, Water melon, Groundnut, Rice.

II. Biennials

A plant that lives for two seasons, growing vegetatively during the first season and flowering and fruiting during the second season. Example: Carrot, Radish, Cabbage.

III. Perennials

A plant that grows for many years that flowers and set fruits for several seasons during the life span. When they bear fruits every year, they are called polycarpic perennials.

Example: Mango, Sapota. Some plants produce flowers and fruits only once and die after a vegetative growth of several years. These plants are called monocarpic perennials. Example: Bambusa, Agave, Musa.

Vegetative Morphology:
Any portion of a plant that is involved in growth, development, photosynthesis, support, etc., but not involved with sexual reproduction.

All plants die eventually. But according to researchers at the New York Botanical Garden in the Bronx, there is no specific lifespan for plants, except for the plants called “annuals,” which are plants that live for one growing season and then die.

The life span of a plant is the length of time it takes from the beginning of development until death, while the life cycle is the series of stages between the germination of the seed until the plant produces its own seeds.

While the concept of form in biology, opposed to function, dates back to Aristotle (see Aristotle’s biology), the field of morphology was developed by Johann Wolfgang von Goethe (1790) and independently by the German anatomist and physiologist Karl Friedrich Burdach (1800).

The two branches of morphology include the study of the breaking apart (the analytic side) and the reassembling (the synthetic side) of words; to wit, inflectional morphology concerns the breaking apart of words into their parts, such as how suffixes make different verb forms.

In this page you can discover 16 synonyms, antonyms, idiomatic expressions, and related words for morphology, like: morphological, patterning, surface structure, ontogeny, phylogeny, ultrastructural, neuroanatomical, microstructure, geomorphology, plasticity and syllable structure.

The internal structure of words and the segmentation into different kinds of morphemes is essential to the two basic purposes or morphology: the creation of new words and the modification of existing words.

Morphology is the study of the internal structure of words and forms a core part of linguistic study today. The term morphology is Greek and is a makeup of morph- meaning ‘shape, form’, and -ology which means ‘the study of something’.

According to the traditional view, the relation between morphology and syntax is the following: while morphology builds up word forms typically by combining roots with other roots and with affixes, but also by applying other operations to them, syntax takes fully inflected words as input and combines them into phrases.

Morphology:
Study of the rules that govern how morphemes, the minimal meaningful units of language, are used in a language.

Semantics:
The meaning of words and combinations of words in a language. The role of morphology in language acquisition and literacy development across languages. Morphemes are the smallest meaning-bearing units of the language. As such, they are the fundamental building blocks for communication during both language and reading development.

Learninsta presents the core concepts of Biology with high-quality research papers and topical review articles.

Plant Habitat and its Various Types

Depending upon where plants grow habitats may be classified into two major categories:

I. Terrestrial and
II. Aquatic

I. Terrestrial

Plants growing on land are called terrestrial plants.

II. Aquatic

Plants that are living in water are called aquatic plants or hydrophytes.

Different Types of Habitat

Forest Habitat:
Forest is a large area covered with plants.

Aquatic Habitat:
Habitat in water is aquatic habitats.

Grassland Habitat:
Grassland is regions dominated by grasses.

Dessert Habitat:
Mountainous and Polar Habitat.

Habitat indicates a specific place where a species or population normally lives in nature, it is a physical area, some particular part of the earth’s surface, air, soil or water.

There are five major biomes found in the world:
Aquatic, Desert, Forest, Grassland, and Tundra.

We will focus on eight habitats:
Polar, Tundra, Evergreen Forests, Seasonal Forests, Grasslands, Deserts, Rainforests, and Oceans. These are global habitats that cover vast areas of the Earth. Of course there are habitats that exist at a smaller scale, like regional, local or micro scale habitats.

Two main types of habitat are water and land. Some animals are more comfortable when they are wet, and others when they are dry!

Examples of Habitats Include:

• Desert
• Meadow
• Woodland
• Grassland
• Forest
• Seashore
• Ocean

The two main types of habitats are terrestrial, or land habitats and aquatic, or water, habitats. Forests, deserts, grasslands, tundra, and mountains are just a few examples of terrestrial habitats.

The area where a particular organism lives naturally is called its habitat. The five major habitats are – forests, grasslands, deserts, mountains and polar regions, and aquatic habitat. Oceans and freshwater together form the aquatic habitat.

The chief environmental factors affecting the habitat of living organisms are temperature, humidity, climate, soil and light intensity.

It’s the entire neighborhood where an animal gets the food, water and cover it needs to survive. Scientists call this home or place its habitat. For humans, habitat may mean the neighborhood or city in which they live.

Different kinds of plants grow naturally in different areas too. Plants and animals will choose where they live mostly because of the water, food and climate of a specific are a habitat is the physical area where the animal or plant lives. An organism’s natural habitat has everything it needs to live.

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Habit and its Various Types of Vegatative Morphology

The general form of a plant is referred as habit. Based on habit, plants are classified into herbs, shrubs, climbers (vines) and trees.

I. Herbs

Herbs are soft stemmed plants with less wood or no wood. Example: Phyllanthus amarus, Cleome viscosa. According to the duration of their life they may be classified as annuals, biennials and perennials. Perennial herbs having a bulb, corm, rhizome or tuber as the underground stem are termed as geophytes. Example: Allium cepa

II. Shrubs

A shrub is a perennial, woody plant with several main stems arising from the ground level. Example: Hibiscus rosa sinensis (shoe flower).

III. Climbers (Vine)

An elongated weak stem generally supported by means of climbing devices are called Climbers (vines) which may be annual or perennial, herbaceous or woody. Liana is a vine that is perennial and woody. Liana’s are major components in the tree canopy layer of some tropical forests. Example: Ventilago, Entada, Bougainvillea.

IV. Trees

A tree is a stout, tall, perennial, woody plant having one main stem called trunk with many lateral branches. Example: Mango, Sapota, Jack, Fig, Teak. If the trunk remains unbranched it is said to be caudex. Example: Palmyra, Coconut.

A habit (or wont as a humorous and formal term) is a routine of behavior that is repeated regularly and tends to occur subconsciously.

The definition of habit is something that you do regularly, or an addiction. Brushing your teeth every morning and every night is an example of a good habit. Being addicted to heroin is an example of having a heroin habit.

Some common synonyms of habit are custom, practice, usage, and wont. While all these words mean “a way of acting fixed through repetition,” habit implies a doing unconsciously and often compulsively.

A hobby is a regular activity that is done for enjoyment. A habit is a regular action or behavior that is acquired through frequent repetition. The key difference between hobby and habit is that a hobby is pursued consciously whereas a habit is often a subconscious act.

Within psychology, the term habit refers to a process whereby contexts prompt action automatically, through activation of mental context-action associations learned through prior performances.

Habits are the things a person does repeatedly until such time that it becomes automatic. While behavior is the reaction of the system on the impulses around it, habit is the thing a person does repeatedly and subconsciously until it becomes a routine. This is the main difference between the two.

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Angiosperms Characteristics and its Silent Features

In the previous section, the characteristic features of one of the spermatophyte called Gymnosperms were discussed. Spermatophytes also include plants bearing ovules enclosed in a protective cover called ovary, such plants are called Angiosperms.

They constitute major plant group of our earth and are adapted to the terrestrial mode of life. This group of plants appeared during the early cretaceous period (140 million years ago) and dominates the vegetation on a global scale. The sporophyte is the dominant phase and gametophyte is highly reduced.

Salient Features of Angiosperms

• Vascular tissue (Xylem and Phloem) is well developed.
• Flowers are produced instead of cone
• The Ovule remains enclosed in the ovary.
• Pollen tube helps in fertilization, so water is not essential for fertilization.
• Double fertilization is present. The endosperm is triploid.
• Angiosperms are broadly classified into two classes namely Dicotyledons and Monocotyledons.

Characteristic Features of Dicotyledons and Monocotyledons

Dicotyledons

Morphological Features

Reticulate venation is present in the leaves. Presence of two cotyledons in the seed. Primary root radicle persists as tap root. Flowers tetramerous or pentamerous. Tricolpate (3 furrow) pollen is present.

Anatomical Features

• Vascular bundles are arranged in the form of a ring in stem.
• Vascular bundles are open (Cambium present).
• Secondary growth is present.

Monocotyledons

Morphological features Parallel venation is present in the leaves. Presence of single cotyledon in the seed. Radicle doesn’t persist and fibrous root is present. Flowers trimerous. Monocolpate (1 furrow) Pollen is present.

Anatomical Features

• Vascular bundles are scattered in the stem
• Vascular bundles are closed (Cambium absent).
• Secondary growth is absent.

Current Angiosperm Phylogeny Group (APG) System of classification doesn’t recognize dicots as a monophyletic group. Plants that are traditionally classified under dicots are dispersed in several clades such as early Magnolids and Eudicots.

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Pteridophytes Types and its General Characteristic Features

Seedless Vascular Cryptogams

From the previous section, we are aware of the salient features of amphibious plants called bryophytes. But there is a plant group called pteridophytes which are considered as first true land plants. Further, they were the first plants to acquire vascular tissue namely xylem and phloem, hence called vascular cryptogams. Club moss, horsetails, quill worts, water ferns and tree ferns belong to this group. This chapter deals with the characteristic features of Pteridophytes.

Pteridophytes are the vascular cryptogams and were abundant in the Devonian period of Palaeozoic era (400 million years ago). These plants are mostly small, herbaceous and grow well in moist, cool and shady places where water is available. The photographs for some pteridophytes are given in Figure 2.6.

General Characteristic Features of Pteridophytes:

1. Plant body is sporophyte (2n) and it is the dominant phase. It is differentiated into root, stem and leaves.
2. Roots are adventitious.
3. Stem shows monopodial or dichotomous branching.
4. Leaves may be microphyllous or megaphyllous.
5. Stele is protostele but in some forms siphonostele is present (Marsilea)
6. Tracheids are the major water conducting elements but in Selaginella vessels are found.
7. Sporangia, spore bearing bag like structures are borne on special leaves called sporophyll. The Sporophylls get organized to form cone or strobilus. Example: Selaginella, Equisetum.
8. They may be homosporous (produce one type of spores-Lycopodium) or Heterosporous (produce two types of spores-Selaginella). Heterospory is the origin for seed habit.
9. Development of sporangia may be eusporangiate (development of sporangium from group of initials) or leptosporangiate (development of sporangium from single initial).
10. Spore mother cells undergo meiosis and produce spores (n).
11. Spore germinates to produce haploid, multicellular green, cordate shaped independent gametophytes called prothallus.
12. Fragmentation, resting buds, root tubers and adventitious buds help in vegetative reproduction.
13. Sexual reproduction is oogamous. Sex organs, namely antheridium and archegonium are produced on the prothallus.
14. Antheridium produces spirally coiled and multiflagellate antherozoids.
15. Archegonium is flask shaped with broad venter and elongated narrow neck. The venter possesses egg or ovum and neck contain neck canal cells.
16. Water is essential for fertilization. After fertilization a diploid zygote is formed and undergoes mitotic division to form embryo.
17. Pteridophytes show apogamy and apospory.

Reimer (1954) proposed a classification for pteridophytes. In this classification, the pteridophytes are divided into five subdivisions.

• Psilophytopsida
• Psilotopsida
• Lycopsida
• Sphenopsida
• Pteropsida.

There are 19 orders and 48 families in the classification.

Economic Importance

The Economic importance of Pteridophyte is given in Table 2.3

Types of Stele

The term stele refers to the central cylinder of vascular tissues consisting of xylem, phloem, pericycle and sometimes medullary rays with pith (Figure 2.7).

There are two types of steles

1. Protostele
2. Siphonostele

1. Protostele:

In protostele phloem surrounds xylem. The type includes Haplostele, Actinostele, Plectostele, and Mixed protostele.

(i) Haplostele:
Xylem surrounded by phloem is known as haplostele. Example: Selaginella.

(ii) Actinostele:
Star shaped xylem core is surrounded by phloem is known as actinostele. Example: Lycopodium serratum.

(iii) Plectostele:
Xylem plates alternates with phloem plates. Example: Lycopodium clavatum.

(iv) Mixed prototostele:
Xylem groups uniformly scattered in the phloem. Example: Lycopodium cernuum.

2. Siphonostele:

In siphonostele xylem is surrounded by phloem with pith at the centre. It includes Ectophloic siphonostele, Amphiphloic siphonostele, Solenostele, Eustele, Atactostele and Polycylic stele.

(i) Ectophloic Siphonostele:

The phloem is restricted only on the external side of the xylem. Pith is in centre. Example: Osmunda.

(ii) Amphiphloic Siphonostele:

The phloem is present on both the sides of xylem. The pith is in the centre. Example: Marsilea.

(iii) Solenostele:

The stele is perforated at a place or places corresponding the origin of the leaf trace.

(a) Ectophloic Solenostele:
Pith is in the centre and the xylem is surrounded by phloem Example Osmunda.

(b) Amphiphloic solenostele:
Pith is in the centre and the phloem is present on both sides of the xylem. Example: Adiantum pedatum.

(c) Dictyostele:
The stele is separated into several vascular strands and each one is called meristele. Example: Adiantum capillus-veneris.

(iv) Eustele:

The stele is split into distinct collateral vascular bundles around the pith. Example: Dicot stem.

(v) Atactostele:

The stele is split into distinct collateral vascular bundles and are scattered in the ground tissue. Example: Monocot stem.

(vi) Polycyclicstele:

The vascular tissues are present in the form of two or more concentric cylinders. Example: Pteridium.