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Neutral: Definition, Types, and Examples
Continue ReadingNeutral Definition
1. Neutral; indifferent; not engaged on either side; not participating with or aiding any of two or more opposing parties. The heart is incapable of being neutral, and it is continuously involved in one way or another. (Shaftesbury)
2. Neither good nor terrible; of average quality; indecisive or pronounced. Some things appear to be nice, while others appear to be bad, and some appear to be neutral in her amazing sight. Sir J. Davies (Sir J. Davies)
3. (science: biology) A Neuter is a word that means “nothing.”
4. (Science: chemistry) Certain salts or other substances are described as having neither acid nor basic characteristics; they are unable to make red litmus blue or blue litmus red. Acid and alkaline are contrasted.
5. (Chemical science) A salt produced by completely replacing the hydrogen in an acid or base with a positive or basic, or a negative or acidic, element or radical; in the former instance, by a positive or basic, in the latter case, by a negative or acid.
In watercolours, a neutral tint is a bluish grey pigment created by combining indigo or another blue with a warm colour. The hues are quite varied. The vowel element of a neutral vowel has an ambiguous and indeterminate character, similar to that of the vowel in many unaccented syllables. Some consider it to be the same as the u in up, and it’s also known as the natural vowel since it’s unformed by art or effort.
Neutral Citations
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Okazaki Fragments: Definition, Mechanism, and Diagram
Continue ReadingOkazaki Fragments Definition
During DNA replication, a relatively small piece of DNA is produced on the lagging strand.
DNA unwinds and the two strands split in half at the commencement of replication, creating two “prongs” that resemble a fork (thus, called replication fork).
The leading strand is 5′ to 3′ long, while the lagging strand is 3′ to 5′ long.
Unlike the leading strand, which may be produced continuously, the lagging strand is generated in small pieces known as Okazaki fragments, which are then covalently linked to form a continuous strand.
This is due to the fact that DNA synthesis can only go in one direction: 5′ to 3′.
Okazaki Fragments Diagram
Reiji Okazaki, Tsuneko Okazaki, and their colleagues first found Okazaki pieces in 1968 while researching bacteriophage DNA replication in E. coli.
It was named after its discoverers, Reiji Okazaki and his wife, Tsuneko Okazaki, who worked on bacteriophage DNA replication in E. coli in 1968.
Okazaki Fragments Citations
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Primary Consumers: Definition, Types, and Examples
Continue ReadingPrimary Consumers Definition
Any organism that eats or feeds on autotrophs is known as an autotroph. A food chain is a feeding hierarchy in which species in an ecosystem are classified into trophic (nutritional) levels and presented in a sequential order to depict the flow of food energy and their feeding connections. It is made up of several trophic levels.
A trophic level is a place or level in the food chain or ecological pyramid. It is inhabited by a collection of creatures that feed in a similar manner. There are three basic ways in which organisms get nutrition in a food chain.
Food is obtained from inorganic sources, organic stuff is fed, and dead organic materials or wastes are broken down.
Producers are those who are capable of acquiring food directly from inorganic sources (or autotrophs).
Consumers are those who feed on organic stuff (or heterotrophs).
Decomposers are organisms that break down dead organic material (or detritivores).
Consumers are creatures that feed on other organisms or organic materials to get nourishment. They lack the capacity to create their own food from non-organic sources, as farmers do.
Consumers in a food chain may be divided into three categories: main consumers, secondary consumers, and tertiary consumers.
Herbivores are the primary consumers. Producers are what they eat. Herbivores that eat green plants, for example, are termed main consumers.
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Angiosperm: Description, Characteristics, and Examples
Continue ReadingAngiosperm Definition
Angiosperm can be defined as those whose fertilized eggs forms seed within the ovary.
What is Angiosperm?
The word Angiosperm originates from a Greek word where “angeion” means vessel and “sperma” means seed. Flower bearing plants are called as Angiosperms. Belonging to the plants group. Along with the flower, it also bears seeds. It is one of the vast group of plants, with 453 families and 260,000 species within. In the category of Angiosperms are 80% of green plants.
In angiosperms, female and male organs are both found. They are found in almost all location, excluding those with extreme climatic condition such as in the depth of the ocean, poles, mountain ranges and etc. while they are present in various climatic conditions, they may be immersed in soil, water or present on the surface or freely floating. They vary in size from very small in millimeters to 100 meters. Example are huge trees to tiny shrubs and intermediary plants. Orchidaceae is the abundant species of Angiosperms. Examples are grasses, pea and daisies. They have applications in various fields such as medicine, wood products, jewelry, industrial products and pharmaceutical products.
Angiosperm Anatomy and Morphology
They belong to the phylum Anthophyta of flowering plants and consist of stamens, carpels and pollens. In flowering plants, pollen grains are the sperms, producing stamens. Within the pollen grain lies the males game which will interact with the female gamete in the plant’s ovaries. Angiosperms can reproduce sexually as well as asexually. As the pollen grains are smaller than that of gymnosperms, thus, reaching the eggs of female quicker. Without fertilization as well angiosperms can undergo the process through pollens; where stamens has a vital role in the flowering plants life cycle of fertilization. Through cross-pollinations, insects get attracted towards the flowers, due to their colors as well as smell.
Behind the flower, are ovaries encapsulated in the carpels. To produce seeds, fruits and flowers, pollens are obtained by the ovaries which starts the process. Thus, the very first step involves seed development, followed by flowers and its pollination to produce fruit. Angiosperms have characteristics that resemble synapomorphies. Within the carpels are the ovules present which carries the pollination process. For the double fertilization to occur and for the endospore formation, it requires pollen sac and three stamens. Sieve tubes and companion cells are present in phloem tissues.
Angiosperm Flowers and Anatomy
For the reproduction to occur, pollination is quite important. The male sex organ are the stamens that produces pollen, which then get translocated to the pistil, which is the part of the female angiosperm.
Angiosperm Flowers Anatomy
Pollination occurs when the pollen from the male reaches the female part. There are two types of pollination; self-pollination and cross pollination. Pollination agents are insects, invertebrates, mammals and wind.
Structure of Angiosperms
The reproductive organ in Angiosperms are flowers and roots, stems and leaves are the asexually reproductive organs. Root system and shoot system are the angiosperm structures. Shoot system is the one present above the soil, whereas the root system is the one that is present in the soil. Root system comes under the root domain whereas the shoot lies under the shoot domain.
Root System
Roots are the most vital part of the plant; without them the plant is nothing. Absorption of minerals, water, nutrient from the soil is the function of the roots and transfer it to the tips. Primary and Tertiary root system are the types of root systems, where taproot is seen which grows towards the ground in length to form roots, which can further grow diagonally and horizontally is the primary root system and from taproots production of more roots is known as secondary roots. Primary roots have a very short life-span, and thus their position is occupied by supplementary system of roots. Depending on the function, primary and tertiary roots gets altered. Examples are beetroot and carrot.
Stem System
To make the plant stand, and on which the fruits and flowers come is the stem. From the roots the nutrients, water and other essential requirements moves to the stem and then to the leaves, fruits, plants and animals. Hypocotyl allows the continuous transfer of nutrients from roots to stem. From the stem, when the leaves are formed it is known as nodes and the distance between two nodes is known as internodes. The type of branching seen in angiosperms are axillary and dichotomous; in axillary there are two types of branching sympodial and monopodial.
Leaves System
From the stem emerges the leaves. For the formation of leaves, lamina is the main part which consist of petiole, stipule and blade. To the petiole the base of the leaf and the blade is linked and on both the sides is the stipule present. From the blade, photosynthesis occurs and thus is green and flattened in shape. However, some leaves shows the absence of petiole and stipules. The pattern on the stem can be opposite, whorled, alternate and paired.
Angiosperm Life Cycle and Reproduction
Double fertilization occurs in the angiosperms, where from the seeds the male and female gametophyte are produced. Sporophyte is the step in the life cycle, where the adult angiosperm is formed are heterosporous. The pollens will be generated from the microspores and the gametophyte are the pollen grains of the male. The female gametophytes which is the ovule will be formed from megaspores. Within the pollen lies two types of cell, one will form the pollen tube and the other will make up sperms.
The ovule is covered by another wall to keep the megasporangium intact, where meiosis takes place to produce a huge and three tiny megaspores, where only the huge megaspore reaches the embryo sac and gets three time divided after which the eight cell further moves. The four cells move towards the equator and the rest move to the pole resulting in the formation of 2n polar nucleus. There are helping cells present which are the synergids, nucleus, antipodal cell and an egg sac which is inside a mature embryo sac. As soon as the pollens reach the stigma, the sperms reaches the embryo sac and double fertilization starts, where the sperm and egg combines to form the embryo, whereas there is fusion of the polar nuclei and the second sperm going on. They form an endosperm, which stores the food.
On the basis of the leaves, angiosperms can be divided into eudicots and the monocots. On the embryo surface there are seed leaves which contain protein, lipid and sugars. There exist three species of angiosperm and they are where on the flower, stamen and pistil are present is the hermaphroditic. Monecious, where both the stamen and pistil are on the same plant but different flower. When both stamens and pistil are present on different plants and different flower it is called as dioecious.
Monocot
In 1703, they were first discovered by Ray. In the seed presence of a single cotyledon are called as monocots. These monocots phylogenetic studies have been done in 19th century. They consist of fibrous system of roots. The flowers in monocots consist of three parts and are called as Trimerous. Woody tissues are either absent or only present in few cases. A vital feature seen in monocots is the presence of a single layer of pollens, which is even seen today. Examples of monocots plant are orchid, lilies, grasses and others, whereas monocot crops are sugarcane, pineapple, corns and others.
Dicot
More than one cotyledon in the seed is the Dicot. The flower in dicot consist of four or either five parts. The network seen in leaf is of reticulate venation type. The vascular tissue present in the ring forms the dicot. They are capable of producing woody tissues. In dicots the pollen consist of three layers. They have taproot system. Dicot examples are sunflowers, beans and oak.
Angiosperm Examples
There are numerous examples of angiosperms, however the most common one are the flowering plants. The most studied example of angiosperm are fruit trees. The fruits are formed from various flowering plants. Grains and grasses are also included in angiosperms. Fruits such as apple, cherries and oranges. However, the insects, birds, wind and mammals are the agents of pollination. After the pollination process get completed and the carpel has opened up, flowers get converted to fruits and will also change colors.
As wheat, rice grow in grasses and they cannot attract pollinators thus, the agent for pollination to take place is wind as they carry the seed because its light in weight. Thus, angiosperms are very vitals as various crops are available to humans because of them.
History of Angiosperm
In the Mesozoic era, the fossil records have been first seen in history. They possess both male and female gametophytes and are the flowering plants. Around 100 million years ago, these plants were identified in the middle cretaceous and were viewed 125 million years prior by the paleontologist. Although there aren’t much traces of history of angiosperm but fossil of pollen has been obtained, and were believed to have quite similarity to angiosperms.
It is said that from the gymnosperms, angiosperm has been arrived, but yet studies are going on, as they form a different set of species on the basis of its features. They believed angiosperms to be originated from tropical grasses or woody bushes.
In the south pacific, there is a rain forest in New Caledonia which has a flowering plant which is quite small and is quite ancient it is the Amborellatrichopoda and is confirmed that is a flowering plant. The other angiosperms are the monocots and the eudicots. Basal angiosperms were also part of the angiosperm, but however have been removed from the category of angiosperm.
Angiosperm Fossil Record
The very first record of the angiosperm fossil is of 132 million years ago. There is quite a lot of differences seen in the size, structure, flowers in the ancient old angiosperms and those of the modern era. Although the only similarity found was in the flowers. Thus, classifying them into the category of Angiosperms.
Estimation of Age of the Angiosperms
This information of how old the angiosperms are since how long they have existed can be identified with the fossil. Modern and molecular techniques have been used to determine the origin of flowering plants and has said that they are 5-45 millions years old. Various researchers have worked on the finding of origination of angiosperm using various tools and techniques and have found that the age of angiosperm is 165-199 Ma and for other plants as well have been found.
Angiosperms Ecological Importance
They have a huge role in various fields, on the environment and on humans as well as animals. The flowering plants are quite important as they keep the food chain continuing. Many insects, birds and other mammals eat these plants. These plants are also source of pollination to other insects. They provide us fruits, flowers along with seed, as many animals can continue lifecycle when they consume the fruits and obtain energy.
The seed propagation takes place when birds and other mammals eat them and take the seeds to various locations, thus resulting in more flowering plants. They also produce various products such as alkaloid, oil and glycosides. They also prevent the predators from causing harm to the other plants and stop them from producing toxic compounds. It is said that thousands of birds, animals get their food the angiosperm tree, thus, they maintain the food chain and keep it running.
Economic Importance of Angiosperm
They have application in various industries which starts from the pharmaceutical industry. Majority of the antibiotics, drugs are either made from angiosperms or are the derivative of angiosperms. Narcotic, vitamins, aspirin and quinine are some of the example. These angiosperms have shown promising results in treating cardiac arrest and various forms of cancer.
For heart surgeries and for relaxation of muscle, curare is used. For treating malaria, quinine is used. For cancer, vincristine has been used and for oral contraceptives diosgenin has been used. They also play a role in preserving the environment. Humans and animals are dependent on angiosperms for food and their absence would have a major impact on the environment as well as on every individual.
Angiosperms vs Gymnosperms
Flowering plants are Angiosperms. Example are grains, fruits, vegetables and others. Gymnosperms are non-flowering plants and their examples are juniper, pine, cedar and fir. Accumulation of gymnosperms form, cones whereas the accumulation of angiosperm forms flowers. Angiosperms are mostly unisexual whereas the gymnosperms are bisexual. In angiosperms there are various flowering parts such as style, stigma, petals and sepals. Archegonia is found in gymnosperms and is absent in angiosperms. On the stalk are the angiosperms present. Angiosperms and gymnosperms also vary in the cotyledon number. Angiosperms have application in food, ornament, timber and pharmaceutical, whereas gymnosperms in making of ply, paper and lumber.
Angiosperm Citations
- Vessel-associated cells in angiosperm xylem: Highly specialized living cells at the symplast-apoplast boundary. Am J Bot . 2018 Feb;105(2):151-160.
- Angiosperm Plant Desiccation Tolerance: Hints from Transcriptomics and Genome Sequencing. Trends Plant Sci . 2017 Aug;22(8):705-717.
- Angiosperm ovules: diversity, development, evolution. Ann Bot . 2011 Jun;107(9):1465-89.
- Key questions and challenges in angiosperm macroevolution. New Phytol . 2018 Sep;219(4):1170-1187.
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Branches of Biology: Definition and Branches
Continue ReadingBranches of Biology
Agriculture: It is the study which deals with natural resources as well as rock.
Anatomy: It is the human body study.
Astrobiology: it is concerned with the impact on living organism of the space.
Biochemistry: It is the study of biomolecules such as carbohydrates, fats, protein, nucleic acid and etc.
Bioclimatology: it deals with the impact of climate on various organism.
Bioengineering: It is concerned with biological processes, system, analysis and designing of product.
Biogeography: it studies the pattern of ancient organism and their fossil.
Bioinformatics: It deals with biology related stored using technology, so that its widely and easily available.
Biology: It can be defined as the study of life and has various subject lying within it.
Biomathematics: This is also an interdisciplinary field, where in biology, tools and techniques of math is used.
Biophysics: It is a field of science which poses questions in biology about physical science.
Biotechnology: it deals with altering processes and products to obtain a modified product.
Botany: It deals with plants.
Cell biology: It deals with the scientific study of cells and its process.
Chronobiology: It is the study of organism related to time.
Conservation Biology: It is the study of conserving and preserving habitat, species and biodiversity.
Cryobiology: It deals with organism thriving at low temperatures are called as Cryobiology.
Development Biology: The study of formation of zygote from an organism is called as Development biology.
Ecology: The interaction between the environment and the organism is called as Ecology.
Entomology: Studying the insects is called Entomology.
Ethnobiology: It is the study of the flora and fauna of the environment.
Ethology: The scientific study of animal behavior is called as Ethology.
Evolutionary Biology: It is the study of the organism and its evolution.
Freshwater Biology: It is the study of freshwater and the organism and its habitat.
Genetics: It’s a field of biology, which deals with variations and heredity of organisms.
Geobiology: It is the combination of two fields, biology and geology, where organism and their interaction with environment is studied.
Herpetology: Studying the amphibian and reptiles is called as Herpetology.
Ichthyology: Studying the fishes is called as Ichthyology.
Immunobiology: It deals with the study of immune system is called as Immunobiology.
Mammalogy: Mammalogy is the study of animals.
Marine Biology: It deals with the study of organism present in plants and animals.
Medicine: It deals with the treatment of the disease.
Microbiology: The study of microorganism is called as Microbiology.
Molecular Biology: The study of various biomolecules such as DNA, proteins, RNA and others.
Mycology: It deals with the fungus study.
Neurobiology: The study of nervous system is termed as Neurobiology.
Ornithology: Ornithology is the study of birds.
Paleobiology: It deals with the study of ancient organisms or their fossils.
Parasitology: It deals with the scientific study of Parasites.
Pathology: Pathology deals with the effects, progress and the process of various diseases.
Pharmacology: It is the study about the drugs.
Physiology: It is the study of biotic entities and their parts and their functions.
Primatology: The study of primates is known as primatology.
Prostiology: studying protist is called as Protistology.
Psychobiology: biological process and its link with the behavior and mental functioning is called Psychobiology.
Toxicology: man-made and natural poisons study is Toxicology.
Virology: Virus study is called as Virology.
Zoology: The study of animal’s growth, identification, structure and their life is called as Zoology.
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Cell Structure: Definition, Function, and Examples
Continue ReadingCell Structure
The nucleus and cytoplasm are two parts of the cell’s interior. The nucleus is a spherical or oval-shaped structure located at the cell’s core. Outside of the nucleus, the cytoplasm comprises cell organelles and cytosol, or cytoplasmic solution. The cytosol and the fluid inside the organelles and nucleus make up the intracellular fluid.
Cell Membrane Structure
Membranes are the cell’s entry points. The cell’s plasma membrane serves as a selective barrier. It acts as a barrier between the intracellular and extracellular fluids, preventing molecules from moving between them. Remember that extracellular refers to the area outside of the cell. The plasma membrane also acts as a connector between cells and the extracellular matrix. Membrane sensitivity and permeability can be altered by a variety of signals and inputs.
Cell Membrane Structure: Fluid Mosaic Model
Membranes are made up of two layers of lipids, the majority of which are phospholipids, with embedded proteins. The embedded proteins play a vital role in facilitating the passage of molecules across the membrane. The membrane is structured as a bimolecular layer, with the non-polar part in the centre (away from water since it is hydrophobic) and the polar regions facing outward: the extracellular fluid and the cytosol.
Another way to see it is as two rows of pins, with the heads on the outside and the needle on the inside. Heads, Needles, Needles, Heads As if it were a sandwich. The overall bi-layer structure has flexible fluidity because the phospholipid molecules are not chemically linked to any other, and therefore, each molecule is free to move freely. Cholesterol molecules are also anchored in the plasma membrane, where they form vesicles that transport chemicals to cell organelles.
There are two types of proteins that are embedded in the membrane.
Peripheral membrane proteins are proteins that interact with cytoskeletal components on the membrane surface, primarily on the cytosolic side, to impact cell shape and motility. These proteins are attached to the polar domains of the integral proteins and are not amphipathic.
Integral membrane proteins cover the whole width of the membrane, allowing them to pass through both the polar and non-polar sections. The lipid bilayer can not be disrupted if these proteins are removed from the membrane.
It’s crucial to remember that membrane functions are determined by the chemical composition of the membrane’s two sides, as well as any asymmetries in composition between the two surfaces, and the specific proteins connected to or linked with the membrane. Monosaccharides are connected to the membrane lipids and proteins by an external surface layer on the plasma membrane. The glycocalyx is a layer that is crucial in the intercellular recognition process.
Membrane Junctions
Integrins are transmembrane proteins that bind to certain extracellular matrix proteins as well as membrane proteins on neighbouring cells. Integrins are proteins that aid in the organization of cells into tissues. They’re also in charge of relaying information from the extracellular matrix to the cell’s interior.
Desmosomes can connect two cells that are nearby but not connected. Desmosomes are dense protein accumulations on the cytoplasmic surface of two distinct cell plasma membranes. They’ve been invaded by protein fibres that have penetrated both cells. Desmosomes’ goal and function is to keep neighbouring cells securely in place in regions that are stretched, such as the skin.
The tight junction is another form of membrane junction. The extracellular surfaces of two neighbouring plasma membranes are physically joined to produce these junctions. Tight junctions are crucial in regions where additional control over tissue functions is required, such as the absorption-related epithelial cells of the gut.
Finally, gap junctions are protein channels that connect the cytoplasms of neighbouring cells. The disadvantage of this “direct connection” is that it only allows for the passage of smaller molecules.
Cell Organelles
The small workhouses within the cell are known as cell organelles. Each cell is responsible for all of life’s operations. By breaching the plasma membrane, homogenising the mixture, and ultracentrifuging it, organelles can be liberated. Organelles vary in size and density, and they settle out at varying speeds.
Most cells have a nucleus in the middle. Some cells, such as skeletal muscle, have numerous nuclei, whereas others, such as red blood cells, do not. The nucleus is the membrane-bound organelle with the greatest size. It is in charge of storing and transferring genetic data, in particular.
A selective nuclear envelope surrounds the nucleus. The nuclear envelope is made up of two membranes that are connected at regular intervals to produce nuclear pores, which are circular holes. RNA molecules and proteins that modulate DNA expression are able to pass through the pores and into the cytoplasm.
An energy-dependent mechanism that changes the width of the pores in response to signals controls the selection process. DNA and proteins bind together inside the nucleus to create chromatin, a network of threads. When a cell divides, the chromatin becomes essential because it gets tightly condensed, creating rodlike chromosomes with entangled DNA.
The nucleolus is a filamentous area located within the nucleus. This is where the RNA and protein components of ribosomes are put together. The nucleolus is an area, not a membrane-bound structure.
Animal Cell Diagram Labelled
Ribosomes are the locations where amino acids are converted into protein molecules. Proteins and RNA make up their structure. Some ribosomes are linked to the granular endoplasmic reticulum, whereas others are seen floating about in the cytoplasm.
Proteins produced on ribosomes attached to granular endoplasmic reticulum are transported to the Golgi apparatus from the lumen (open space inside the endoplasmic reticulum) for secretion outside the cell or distribution to other organelles. Free ribosomes produce proteins that are discharged into the cytosol.
The endoplasmic reticulum (ER) is a network of membranes that surrounds a single continuous area. As previously stated, granular endoplasmic reticulum is linked to ribosomes (giving the exterior surface a rough, or granular appearance). Rough ER is another name for granular endoplasmic reticulum. The granular ER is involved in Golgi apparatus protein packaging. The agranular, or smooth, ER is the location of lipid production and lacks ribosomes. Agranular ER also accumulates and releases calcium ions (Ca2+).
Plant Cell Diagram Labelled
The Golgi apparatus is a membrane-bound sac that modifies and sorts proteins into secretory and transport vesicles. The vesicles are subsequently transported to the plasma membrane and other cell organelles. Although some cells have numerous Golgi apparatuses, most cells have at least one. The apparatus is typically found close to the nucleus.
Endosomes are tubular and vesicular structures that are membrane-bound and situated between the plasma membrane and the Golgi apparatus. By pinching off vesicles or fusing them, they sort and direct vesicular traffic.
Mitochondria are among the most vital organs in the human body. They are the location of a number of chemical reactions that take place during the production of energy packets known as ATP (adenosine triphosphate). There are two membranes that surround each mitochondrion. The outside membrane is smooth, while the inner membrane is folded into cristae-like tubule formations.
Mitochondria are unusual in that they include a small quantity of DNA that contains the genes for the production of certain mitochondrial proteins. Only the mother’s DNA is passed on to the children. Cells with higher activity have more mitochondria, whereas cells with lower activity require fewer energy-producing mitochondria.
A single membrane connects lysosomes, which contain a highly acidic fluid. The fluid contains digestive enzymes that aid in the breakdown of germs and cell waste. They serve a crucial function in the immune system’s cells.
A single membrane also binds peroxisomes. They absorb oxygen and use it to fuel processes that produce hydrogen peroxide by removing hydrogen from different compounds. They are necessary for the cell’s chemical equilibrium to be maintained.
The cytoskeleton is a filamentous network of proteins that are involved in maintaining and changing cell shape as well as cell mobility. The cytoskeleton also creates tracks for cell organelles to move along, which are pushed by contractile proteins on their different surfaces. Inside the cell, it’s like a mini-highway system. The cytoskeleton is made up of three kinds of filaments.
Microfilaments are the cytoskeleton proteins that are the thinnest and most numerous. They are made up of actin, a contractile protein that can be swiftly built and disassembled to meet the demands of the cell or organelle structure.
Intermediate filaments have a somewhat bigger diameter and are present in greater numbers in areas of cells that will be stressed. Filaments will be seen in desmosomes in the skin. These filaments can not be disassembled quickly after they have been assembled.
Microtubules are hollow tubes made out of tubulin, a protein. They are the most stiff and thickest of the filaments. Axons and long dendritic projections of nerve cells include microtubules. They can quickly assemble and disassemble depending on the situation. Microtubules are organised around the centrosome, which contains two centrioles made up of nine sets of fused microtubules. When the centrosome creates the microtubluar spindle fibres required for chromosomal separation during cell division, they are crucial.
Finally, cilia are motile projections on the surface of certain epithelial cells that look like hairs. They feature a 9-set fused microtubule core in the centre. These microtubules cause cilia to move when they interact with a contractile protein. The luminal contents of hollow organs lined by ciliated epithelium are propelled by ciliar motions.
Cell Structure Citations
- The impact of cell structure, metabolism and group behavior for the survival of bacteria under stress conditions. Arch Microbiol . 2021 Mar;203(2):431-441.
- Endoplasmic Reticulum-Mitochondrial Contactology: Structure and Signaling Functions. Trends Cell Biol . 2018 Jul;28(7):523-540.
- Tight Junction Structure and Function Revisited. Trends Cell Biol . 2020 Oct;30(10):805-817.
- Rethinking cell structure. Proc Natl Acad Sci U S A . 1995 Jun 6;92(12):5251-7.
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Fecundity: Definition, Types, and Examples
Continue ReadingFecundity Definition
Fecundity is a measure of fertility in biology. It might also refer to the ability to reproduce or generate growth. It can be quantified in demography by counting gametes, seed set, or asexual propagules.
What is Fecundity?
The reproduction rate (fecundity rate) or the performance of a person or a group is what fecundity means. What does the term “fecundity” mean in biology? Fecundity is a measurement of a person’s ability to generate gametes. Fecundity, to put it another way, is the measurement of the quantity of new individuals added to a population.
Demographers describe this in a different way. Fecundity is defined as (1) the possibility of being pregnant or (2) the chance of being exposed to becoming pregnant, which is mostly determined by sexual pattern and preventative measures performed.
Fecundity in humans is proportional to the time between female menarche and menopause. The availability of resources and the availability of potential mates have an impact on fecundity.
Fecundity is defined as a female’s ability to generate children during a particular reproductive cycle.
Reproductivity (synonyms: reproductive output; reproductive potential; fertility) is a word that contrasts with fecundity and refers to the number of people or the proportion of the population that has been depleted or perished during a given period of time.
Fecundity vs Fertility
Fecundity is sometimes mistaken for fertility, and vice versa, although the two words are not interchangeable.
Fertility is the quantity of offspring produced by a community or an individual, whereas fecundity is the ability of a person or population to create offspring. Fertility refers to the quantity of children produced rather than the pace of reproduction.
Fertile refers to a person who is capable of reproducing. Fecundity is a person’s inherent capacity to reproduce, which is determined by their health, the availability of good foods, and genetics. Fertility, on the other hand, is the number of children born to a couple in a population.
Fertility is influenced by a variety of factors, including lifestyle, stress, emotional and reproductive health, willingness, the availability of a prospective mating partner, and the use of preventative measures.
Fecundity is not synonymous with fertility, as the capacity to reproduce is influenced by a variety of cultural, environmental, and physiological variables.
In every community, whether animal or plant, a complete or 100 percent translation of fecundity into fertility is rarely achievable.
Fecundity is a developmental and genetic characteristic that progresses according to a set of rules.
Fertility and fecundity are two words that are sometimes used interchangeably, although they have different meanings. Not all pregnancies result in a live child being born. In this context, conception is linked to a couple’s fertility. The couple’s fertility, on the other hand, is their ability to create living babies. Despite the differences in use, the phrases fecundity and fertility are frequently used interchangeably.
How to Calculate Fecundity?
The method for calculating fecundity differs by species and manner of reproduction. For viviparous creatures like placental mammals, fecundity is generally expressed as the number of litters produced each year. In oviparous species, fecundity is usually measured by counting eggs in nests or oviposition sites.
The count of oocytes from a spawning female is used to evaluate fecundity in aquatic animals (excluding mammals and reptiles). To calculate fecundity in highly fecund spawners, a gravimetric or volumetric technique is used to extrapolate the proportion of ovarian tissue of known weight/volume and the resulting oocyte densities to the entire weight/volume of the ovary. Fecundity is also measured by the size of oocytes.
To calculate fecundity in humans, the day-specific probabilities of conception in relation to the day of ovulation, as well as the evaluation of time to pregnancy, are used.
Importance of Fecundity
The net reproduction rate is an essential ecological metric that takes fecundity into consideration. The net reproductive rate is the average number of kids that a female can produce over the course of her reproductive life, taking into account fertility as a function of age and the rate of mortality over time.
Energy Investment
An estimate of population fecundity increases the capacity to convert reproductive physiology research into predicted fertility impacts. As a result, fecundity is a crucial metric to investigate in ecology and animal biology. In ecology, fecundity is also a measure of the quantity of energy expended on rearing a child.
Fecundity is inversely related to the quantity of energy used, as a general rule. To put it another way, the higher the fecundity, or capacity to reproduce, the less energy is required to raise children, or parental care.
According to this rule, there are two possibilities: (1) a population group that can reproduce in greater numbers, and (2) a population group that can only reproduce a few offspring throughout their lives. As a result, according to the inverse fecundity and energy rule:
Organisms that can generate a high number of offspring require a relatively modest amount of energy expenditure. In terms of parental care, most kids are capable of looking after themselves from a young age and do not require much parental involvement in their growth. In such a circumstance, the “survival of the fittest” idea kicks in, and the parents’ energy investment in their offspring’s survival is minimal. The field of marine ecology is a good illustration of this.
Hundreds of eggs are laid by sea urchins, sea snails, and even most fish. In one cycle, a sea urchin may lay 100,000,000 eggs!! These creatures are unconcerned with the survival of each of their young.
Organisms that can generate few children and are strongly involved in each offspring’s survival require a large energy input in each offspring as well as extensive parental involvement. Here, parents expend a great deal of effort to secure the survival of their children. This category includes all animals, including humans. The panda is an example of an animal with low fecundity, as it can only produce one child in a single reproductive cycle. At the time of birth, the child is entirely helpless and fully reliant on their mother for their developmental requirements. Such animals devote a significant amount of energy to the growth, care, and protection of their offspring until they reach adulthood.
The Plant Kingdom follows the same inverse fecundity and energy laws as the Animal Kingdom. Of course, the energy investment here is not in the form of parental care, but rather in the form of energy-dense, high-quality seeds.
Plants with low fecundity will produce a small number of high-energy seeds, which will have a greater or maximum chance of surviving, such as coconuts. Plants with higher fecundity, on the other hand, generate a huge number of seeds (e.g., dandelion), but each seed has a limited quantity of energy. As a result, these seeds’ prospects of survival are slim.
Reproductive Time
The timing of reproduction is another essential element of fecundity and ecology. Depending on when an organism begins to reproduce, the population may be split into two main groups:
• Early Reproducer: When an organism/individual begins reproducing at a young age, their maximal energy is used in the act of reproduction, and they do not expand in size. These creatures, on the other hand, are at the lowest chance of producing no offspring. Such creatures often live for a short period of time. Guppies, for example, are tiny fish.
• A late Reproducer has a higher fertility and a longer lifetime than an entity or individual who begins reproducing later in life. Examples include sharks, bluegill, and other fish.
Parity
The number of individuals that can reproduce in a given lifetime is referred to as parity. Some creatures can only reproduce their offspring once in their lives, whereas others can reproduce numerous times. As a result, fecundity can take one of two forms:
i. Semelparity
When an organism or person reproduces just once during its lifetime, it is said to be semelparous. Such creatures expend all of their energy in order to reproduce, after which they die. Bacteria, bamboo plants, and chinook salmon are all examples.
Various organisms take different amounts of time to reproduce; some may begin reproducing in as little as half an hour (e.g., some bacteria) or as long as a year (e.g., certain mammals after years of reaching reproductive maturity). In all cases, however, the individual dies after reproduction.
Semelparity may be seen in two marsupial families: Didelphidae and Dasyuridae. Following a very synchronised mating season, the male members of some semelparous species die out.
The development of low male semelparity is thought to have resulted from severe male-male rivalry produced by monoestrous reproductive patterns, high estrus synchronisation, and a short mating season. Furthermore, in certain species, a protracted breastfeeding period leads to a high female death rate, resulting in female semelparity.
ii. Iteroparity
Iteroparity refers to an organism or person who reproduces numerous times during their lifespan. Humans and primates are included in this group. Throughout their reproductive lives, many species can reproduce several times.
Reproductivity, on the other hand, begins after the reproductive system has matured. The age or length of time it takes to attain reproductive maturity varies by species (from days to years). Iteroparity can also be categorised as (depending on the frequency of reproduction).
1. Daily: For example, certain tapeworms
2. Semi-annually/ Annually/ Biennially: Some iteroparous creatures only generate offspring every other year. As a result, they do not use a major portion of their reproductive life span. The term for this occurrence is “low frequency of reproduction.” Willow tits (Parus montanus), chubby dormice (Myoxus glis), and kittiwakes (Rissa tridactyla) are examples of these species. The low rate of reproduction is thought to be an ecological phenomenon aimed at increasing average fecundity.
3. Irregularly: For example, humans.
In iteroparity, fertility rises with age before gradually declining. As a result, once the organism reaches reproductive maturity and is ready to produce its first child, it stops developing. This is so that they may devote all of their energy to the process of reproduction. This is an example of an ecological pattern that promotes fecundity.
The term ‘primiparity,’ which refers to the age of first reproduction, was coined as a result of this notion. Ecologically, if an individual/organism does not cease developing throughout its reproductive age, the progeny’s survival rate is likely to be poor.
Both the father and the children would be physiologically incapable of withstanding the pressures of the environment, i.e., the survival of the fittest. As a result, organisms or people that are unsuitable or incompetent will be removed from the system.
Factors Affecting Fecundity
The following are some of the elements that influence fecundity. Body size, environmental circumstances, and mating partner selection are among these influences.
i. Allometric Scaling or Effect of Body Size on Fecundity
The difference in body mass across individuals or species is caused by a variety of variables, including metabolic rate, dispersion capacity, survival likelihood, and fecundity. It’s crucial to remember, though, that the ratio of combined offspring mass to mother mass tends to be fairly consistent within a species. This indicates that bigger females have more fecundity and produce larger children. As a result, a bigger body offers large-bodied mothers and their progeny a selection advantage.
ii. Environmental Conditions
Environmental factors have an impact on fertility. Environmental factors can have an impact on mothers’ health and survival. As a result, fecundity is affected.
iii. Choice of the Mating Partner
Mate selection theory is based on the idea that a female might choose a better mating partner in order to improve her fertility. The ability to select a superior mating partner has been related to the production of genetically healthy and higher-quality offspring with high fertility.
Multiple mating is common in certain animals. This is connected to choosing a superior mating partner once again.
Multiple mating, on the other hand, can be a very energy-intensive activity for females. Multiple mating improves fecundity because mating stimulates egg production, fresh sperm assist in maintaining egg fertility, and the egg production rate rises with mating.
Sperm-sperm competition is the outcome of multiple mating. Two sperm fight for the ova’s attention. The sperm that appears to be superior will eventually merge with the egg, according to the idea of survival of the fittest. This leads to the development of a zygote with a genetic makeup that is likely to be viable. Fecundity is generally higher in men than in females.
Significance of Fecundity Measurements
Fecundity is an important factor to consider when researching the population composition model. Studying population fecundity, fertility, and survival rates is equally essential to understanding the life cycle strategy and the factors impacting it.
Different models are used to investigate their combined influence on a population’s life history strategy. The stage-structured matrix population model is one such model. This model uses stage-specific estimates of vital rates (birth, growth, maturation, fertility, and death) to quantitatively describe population dynamics and provide a connection between the individual (and its selection forces) and the population.
This model generates a stable stage distribution, which represents a theoretical population composition with a fixed birth rate. As a result, variables such as environmental variation or any other intrinsic regulatory element that alter the theoretical population composition may be graded in order to analyse and forecast their impact on population composition.
This model also considers fecundity, fertility, and survival rates to determine each individual’s contribution to the population’s future status. This is referred to as the reproductive value, which is the total of current and future reproductive values.
Reproductive value is the money utilised by nature to produce a certain life-history strategy, according to natural selection theory. Because reproductivity must be maximised by natural law, the population model includes fecundity.
Changes in fertility (and survival) to population growth provide a stage-specific sensitivity analysis in matrix models. The reproductive value at a given stage is determined using this approach as the product of the sensitivity of all matrix components containing that stage and the stable stage percentage.
As a result, a short-lived species has a higher fertility sensitivity than a long-lived one. Long-lived animals, on the other hand, are more sensitive to survival than to fecundity. As a result, the factors that influence population composition may be investigated.
Fecundity Citations
- Fecundity and life-history strategies in marine invertebrates. Adv Mar Biol . 2002;43:87-170.
- Fecundity and natural fertility in humans. Oxf Rev Reprod Biol . 1989;11:61-109.
- Evolutionary Genomics of High Fecundity. Annu Rev Genet . 2020 Nov 23;54:213-236.
- Endocrine disrupting chemicals: Impacts on human fertility and fecundity during the peri-conception period. Environ Res . 2021 Mar;194:110694.
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Continue ReadingGround Tissue Definition
Any of a vascular plant’s non-dermal, non-vascular tissue.
What is Ground Tissue?
There are three fundamental types of specialised (differentiated) tissues in vascular plants: dermal tissues, vascular tissues, and ground tissues.
A ground tissue is a type of plant tissue that is not found in the dermal or vascular tissues. It is produced by the ground meristem. It fills in the plant’s soft components, such as the cortex, pith, pericycle, and so on.
A ground tissue is made up of three different types of cells: parenchyma, sclerenchyma, and collenchyma cells. The nature, shape, and composition of the cell walls are used to classify these cells.
The main walls of parenchyma cells are rather thin. Even when they reach adulthood, the majority of them are still living. In ground tissues, they are the most frequent kind of filler cell.
They can be found in the cortex and pith of stems. They occupy the cortical area in roots.
They also make up the leaf mesophyll. Parenchymatous cells can also be found in the endosperm of seeds and the pulp of fruits. The parenchyma cells provide a number of purposes. Photosynthesis, storage, and secretion are just a few of their primary activities.
Collenchyma cells have a thicker main cell wall than other cells. In contrast, sclerenchyma cells have a secondary cell wall.
Sclerenchyma cells deposit a secondary cell wall between their primary cell wall and plasma membrane in addition to the primary cell wall. When they reach maturity, their walls are lignified and they are dead.
The plant’s structure is supported by both collenchyma and sclerenchyma cells. Sclerenchyma cells, on the other hand, are the primary supporting cells in many plants.
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Continue ReadingHomozygous Definition
(genetics) Of or relating to an individual (or a situation in a cell or organism) with two copies of the same allele for a certain characteristic located at comparable loci on paired chromosomes.
The word homozygous refers to individuals who have the same or identical alleles for a given characteristic at comparable loci on paired chromosomes (i.e. homologous chromosomes).
There are two sets of chromosomes in a diploid organism. One pair is inherited from the mother, while the other is inherited from the father.
Based on their locations, each maternal chromosome has a matching paternal chromosome. Homozygous means that the loci in the corresponding chromosomes have the identical alleles. It indicates that the alleles have the same characteristic coded for them.
A ‘homozygous’ organism is discovered to have either a pair of dominant alleles (e.g. AA) or a pair of recessive alleles for a particular trait (e.g. aa).
True breeding organisms are homozygous because they generate the same phenotypic outcome regardless of the characteristic in issue. The words homo and zygous come from the Greek homo (“same”) and zygous (“young”) (of a zygote)
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Continue ReadingLight Energy Definition
It is a type of energy, which has an impact on the organism and have properties similar to wave and these photons are in the form of particle. The unit is joules for expressing the light energy. 400- 700 nm is the wavelength of light that is cannot be viewed with human eye and is called as visible range of the electromagnetic range.
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Other types of energy are Luminous energy, Radiant energy and Electromagnetic energy.
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