VIRUSES, AND THE TWO CLASS OF FLOWERING PLANTS Summarized Biology Notes

BIOLOGISEDTEAM™

8 Apr, 2022

This Should Take You 4 Hours To Study, If It Takes You More Than Expected, You Should Not Panic At All As We All Learn At Different Pace)

WHAT DO WE MEAN BY DIVERSITY OF ORGANISMS

Hence the term 'Diversity' which if you'll pay attention closely you'll know means 'Divide' in todays post we gonna look closer on how organisms are divided according to the hierarchical system we discussed in the previous post, we'll also look at how different organisms adapts to their habitats and so forth, if you are excited to learn about organisms division then follow along

VIRUSES

Viruses are totally different from all the organisms in the five kingdoms, thus do not qualify to be classified as living organisms that's why we didn't include them in the five kingdom we previously discussed, here is a link to our previous post if you did miss it. The image below shows the structure of the virus, before you continue make sure you master it carefully, don't memorise know what you are reading.

Viruses are extremely small, ranging in size from 30 nm to 300 nm (1/100 compared to a size of a bacterium which makes viruses much smaller than a bacteria), Viruses are said to be non-cellular as they are not made up of cells, they got no nucleus, no cytoplasm, no cell organelles or cell membranes which are common to all living cells, Some viruses however have a membrane outside their protein coats. Viruses are made up of a single central strand of either DNA or RNA surrounded by a protein coat. All viruses are parasitic and do not have a metabolism of their own, meaning that their particles are not cells, they don't carry out nutrition, respiration, excretion, movement, sensitivity nor growth they only can reproduce when they invade in a host cell with it's genetic material, this host cell could be an animal, plant or bacterium cell. When they are inside a host cell they take over all activities of the cell, they use the cells energy and genetic bacterials and make copies of themselves, host cells are killed as they reproduce within them. Viruses are responsible for causing diseases in plants and animals, for example tabacco mosaic virus attacks the tabaccos and tomatoes leaves, where in humans viruses cause diseases such as rabies, colds, polio and AIDS.

The are arguements for and against classifying viruses, some scientists think viruses are living organisms because although they do not carry out nutrition, respiration, excretion, movement, sensitivity and growth, they still can reproduce which is an activity that no other non-living thing can do. While other scientists appose this idea by saying that viruses are not living because although they can reproduce, they do not carry out all seven characteristics of life to be classified as living and they cannot reproduce on their own, they need living cells to do so, for this reason they are not cells! It is believed that viruses accupy the borderline between living and non-living organisms, but arguements against classifying them as living organisms overwhelm arguements in favour of viruses being classified as living, therefore viruses are not living organisms.

Down We'll Look At How Viruses Reproduce, I Used Simple Images To Make It More Understandable

•First: The virus sticks to the membrane of a suitable host cell

•Second: The virus will enter the cell, and the protein coat breaks down and releases the DNA or RNA

•Third: The viral DNA or RNA replicates using host cellular machinery

•Fourth: The host cell is redirected to make new protein coats

•Fifth: The new viruses escape from the host cell wrapping themselves in pieces of the hosts cell membrane as they do so

FLOWERING PLANTS

Flowering plants have roots, stems and leaves, they reproduce by producing seeds that develop from the flower, flowering plants are also many celled or multicellular organisms. Their cells are made up of cell walls, a nucleus and chloroplasts which contain chlorophyll. They feed by absorbing mineral salts and water from the soil and air from the atmosphere which they convert into food using light energy from sunlight in the process we call photosynthesis. Down is the typical general structure of a flowering plant

The are thousands of plants that bear flowers like beans, tomatoes, cabbages, maize plants, wheat plants, acacia trees, grass, water lilies, guava and pawpaw plants. Flowers are the sex organs of plants, flowering plants produce seeds within the fruits, new plants grow from this seeds. The correct name for flowering plants is ANGIOSPERMS, hence the fact that they produce seeds inside their fruits. Now remember the hierarchical classification system if we were to use it we would say

their KINGDOM is PLANTS, PHYLUM as FLOWERING PLANTS but in different CLASS, they are only two CLASS of flowering plants, namely the MONOCOTS (monocotyledons) and DICOTS (dicotyledons) plants, so if you go down you'll get to their species too, but for now we end there, we'll discuss that later in the course down we'll differentiate this two classes of plants

MONOCOTYLEDOUS PLANTS

This plants usually have long, narrow leaves with parallel veins, they contain one seed leaf called cotyledon inside their seeeds hence the name monocotyledon, Mono means one and Cotyledon is the structure inside the seed that stores food. Therefore monocotyledon litterally means one cotyledon or one seed leaf. If you look at flowers of monocotyledonous plants, their petals and sepals are indistinguishable, flower parts are in groups of three, wuth sepals and petals normally joined to form a perigone, you also can identify monocots using their roots, they have an adventitious fibrous root system which grows from the base of the stem, this type of root sytem is shallow, monocotyledonous plants are mostly cereal plants like maize, millet, sugarcane and mahangu, grass also is a monocotyledonous plant

Real Life Examples

Maize Plant

Sugarcane Plant

Simplified Features Of Monocotyledonous Plants

Seed: Single Or One Cotyledon

Root: Root xylem and phloem in a ring

Root System: Fibrous root system

Stem: vascular bundles scattered in stem

Leaf: Leaf veins form a parallel pattern

Flower: flower parts are in three and multiples of three

DICOTYLEDONOUS PLANTS

Dicotyledonous plants are different from Monocotyledonous ones in that they have broad leaves with branching or netwoek veins, they contain two cotyledons inside their seeds as opposed to Monocotyledonous that contain only one. 'Di' means two and as discussed before 'Cotyledon' the structure that store food inside the seed, hence the name Dicotyledonous. If you look at flowers of Dicotyledonous plants you'll notice that their petals and sepals are clearly distinguishable, furthermore, their petals are arranged in groups of four or five. Their root system comprises of a main root called the taproot, with branching roots known as lateral roots which devolop from the taproot, this root system grows deep in the soil, famous example of this plant is the Carrot, daisies, bean and mango

Real Life Examples