Botany

Stem: Features, Types, Functions, and Modification For class 11th and NEET

A) Herbs: ‘Herbs’ are little plants with soft, succulent, green, and less branching stems. Example, Sunflower, and paddy.
B) Shrubs: Shrubs are medium-sized plants with a hard, woody stem that is branched and has a bushy appearance.Example Hibiscus, and Custard apple.
C) Trees: ‘Trees’ are huge, tall plants with very hard, woody stems that have distinct trunks and are densely branched. Mango and Eucalyptus are two examples.

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DNA REPLICATION: DNA STRUCTURE, DNA-Dependent DNA Polymerase, Leading and Lagging strand

DNA REPLICATION: Definition During cell division, DNA replication occurs. It’s bidirectional, discontinuous, and semi-conservative (semi-conservative mechanism was demonstrated by Meselson and Stahl in 1958).DNA replication is a critical mechanism for an organism’s cell development, repair, and reproduction. OVERVIEW OF DNA STRUCTURE James Watson and Francis Crick established the structural model of DNA for the first

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DNA Packaging: Definition, Histone proteins, and Non-Histone proteins

Why is it necessary to package DNA?
The DNA is around 3 meters long and must fit into the nucleus, which is only a few micrometers in diameter. The DNA molecules must be packed into an incredibly compressed and compact structure called chromatin to fit into the nucleus. The DNA is reduced to an 11 nm fiber during the earliest phases of packaging, which represents approximately 5-6 folds of compaction. This is accomplished by packaging nucleosomes in a specific order. DNA packaging is divided into three categories.
1. The nucleosome is the first-order DNA packing.
2. Solenoid fiber is a type of second-order DNA packing.
3. Scaffold loop Chromatids Chromosome is the third order DNA packaging.

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Chromosome- Structure, Types, and Functions for Class 12th and NEET students

The Role and Importance of Chromosomes
Storage of Genetic Code: The genetic material essential for the organism’s development and growth is stored in the chromosome. A series of components called genes make up DNA molecules. Genes are regions of DNA that code for certain proteins that the cell needs to function properly.
Sex Determination: Humans have 23 pairs of chromosomes, one of which is designated as the sex chromosome. The gender of a child is determined by the chromosome passed down by the father. The child will be female if the X chromosome is passed out of the XY chromosome, and a male child will develop if the Y chromosome is passed out of the XY chromosome.
Control of Cell Division: During the process of mitosis, chromosomes check for successful cell division. The parent cells’ chromosomes ensure that the necessary information is passed on to the daughter cells that the cell needs to grow and develop properly.
Protein Synthesis and Storage: Chromosomes direct the sequences of proteins synthesized in our bodies and also keep DNA in order. The proteins are also kept in the chromosomes’ coiled shape. These proteins that are linked to DNA aid in the correct packaging of DNA.

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Mutation: Definition, Types, Effects, and Examples

Aneuploidy: It is characterized by the loss or gain of a chromosomal set. It’s a situation in which one or a few chromosomes are added or removed from the usual amount of chromosomes. As a result, the number of chromosomes in aneuploidy can differ from the number of chromosomes in the wild type.
Nullisomy, monosomy, and trisomy are three different kinds of aneuploidy.
1. Nullisomy (2n-2) is the lack of both homologous pair chromosomes. Most creatures may die as a result of these conditions.
2. Monosomy (2n-1) is the loss of one of the homologous pair’s chromosomes.
3. Trisomy refers to the addition of a second chromosome (2n+1). Trisomy includes conditions such as Klinefelter syndrome (44+XXY/XYY) and Down syndrome.

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Photo-Phosphorylation: Cyclic and Non-cyclic and Effects of Red Drop and Enhancement

Effects of Red Drop and Enhancement
Emerson and Lewis’ demonstration of the red drop proved perplexing. Because the quantum yield only measures the light that has been absorbed, this is not attributable to a decrease in light absorption. This means that light with wavelengths longer than 680 nm is inefficient compared to light with shorter wavelengths. After modifying their fluorescence rates to give equivalent rates of photosynthesis, Emerson and his colleagues evaluated photosynthesis using red and far-red light in subsequent tests. The quantum yield obtained by combining red and far-red light was substantially higher than the sum of the yields obtained by combining red and far-red light separately. Emerson enhancement effect, or Emerson effect, is the name given to this occurrence.
These perplexing red drop and amplification effects led to the conclusion that photosynthesis involves two separate reaction centres or photochemical activities. Red light ( 680 nm) drives one event, while far-red light (> 680 nm) drives the other. When both activities are driven simultaneously or in rapid succession, optimal photosynthesis occurs. These two photochemical reactions are now referred to as Photosystem II and Photosystem I, and they work in tandem to optimise photosynthesis. Photosystem II absorbs red light with a wavelength of 680 nm well but is poorly driven by far-red light. Photosystem I, on the other hand, prefers to absorb far-red light with wavelengths larger than 680 nm.

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Photosynthesis: Light Reaction, The Electron Transport, and  Water Splitting

Light Reaction
The photochemical phase is also known as the light reaction. It involves the absorption of light, the splitting of water, the release of oxygen, and the production of high-energy chemical intermediates (ATP and NADPH). The process involves a large number of complexes.
Within Photosystem I (PS I) and Photosystem II (PS II), the pigments are arranged into two distinct photochemical light-harvesting complexes (LHC). The photosystems are called according to the order in which they were discovered, not their function during the light reaction.
Except for one molecule of chlorophyll a, each photosystem contains all of the pigments. The reaction centre is formed by a single chlorophyll molecule. PS I is named after the reaction centre chlorophyll a, which has an absorption peak at 700 nm. PS II has an absorption maximum at 680 nm, hence the name PS680.

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Photosynthesis: Definition, Early Findings, and Pigments

Photosynthesis is important since
1. 1. It is the principal food source.
2. It releases oxygen into the environment.
Early Findings
1. Jan Ingenhousz: Experiment with aquatic plants in light and dark – He discovered that sunlight is required for plant purification activities.
2. Julius Von Sachs: Plants produce glucose and store it as starch in their green portions.
3. T.W. Engelmann: Spilt light utilising prism into 7 colours (VIBGYOR) – Green Algae Cladophora in a suspension of aerobic bacteria – Bacteria were utilised to detect O2 evolution sites.
4. Cornelius van Niel: He experimented with purple and green bacteria and established that photosynthesis is a light-dependent process in which CO2 is reduced to carbohydrates using hydrogen from H2O. He concluded that oxygen comes from H2O, not CO2.

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Factors Affecting Photosynthesis | Class 10th, 11th, and NEET

Concept of Cardinal Values: Numerous environmental elements affect metabolic processes. The magnitude of each element affects the rate of a metabolic process. Sachs (1860) identified three crucial values for each factor, referred to as the cardinal values or magnitude points. These are the minimal, optimal, and maximal values. The cardinal minimum value is the factor magnitude below which the metabolic process cannot proceed.
The optimal value is the one at which the metabolic process is most rapid. The maximum is the magnitude of a factor at which the process comes to a halt. A metabolic process’ rate declines at magnitudes below and above the optimum until the minimum and maximum values are attained.

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