E-Lecture - Important Point
- Angiosperms are commonly known as group of “flowering plants”. The angiosperms is one of the most highly evolved group of Spermatophyta. They are vascular seed bearing plants in which ovules are enclosed in the ovary wall.
- Classification of Angiosperms is based on the types of cotyledon present, angiosperms are divided into two classes. They are monocotyledons and dicotyledons. The dicotyledonous angiosperms have two cotyledons in their seeds and the monocotyledonous angiosperms have one cotyledon.
- The success of angiosperms is due to two novel reproductive structures: flowers and fruits. The function of the flower is to ensure pollination, often by arthropods, as well as to protect a developing embryo.
- Plant tissues can be grouped into plant tissue systems each performing specialized functions. The plant tissues are differentiated into three main tissue types: dermal, ground and vascular tissue. Ground tissue is often divided into Collenchyma, sclerenchyma, and parenchyma. The vascular tissue consists of xylem and phloem.
- A typical plant body consists of three basic organs: roots, stems, and leaves. A root is the underground part of a plant and the organ that anchors a plant to the ground. A root absorbs water and minerals. Roots are also modified to perform different functions.
- The main function of the stem is to bear branches and leaves and to give them proper exposure to sunlight. The leaves help the plants to absorb sunlight and carbon dioxide for manufacture of food. Leaves of certain plants become wholly or partially modified for defensive purpose into sharp, pointed structures known as spines - to protect plants from grazing animals.
- The arrangement of leaves on a stem is known as phyllotaxy. Leaves are classified as either alternate, whorled or opposite. Seed germination is a process where a seed develops and grow into new plants.
- Double fertilization, in flowering plant reproduction, the fusion of the egg and sperm and the simultaneous fusion of a second sperm and two polar nuclei that ultimately results in the formation of the endosperm of the seed. This is called double fertilization and is unique to flowering plants.
- Fruit is a mature ovary and its contents. Fruits and seeds dispersal is the process whereby fruits and seeds are scattered from their origin.
- Plant hormones control all the growth and development activities like cell division, enlargement, flowering, seed formation, dormancy and abscission.
- An instrument called ‘Lever Auxanometer measures the rate of growth of plant in terms of short length.
- Vascular plants transport systems consist of two main systems which are the xylem and phloem.
- Carbon dioxide, excess water produced during respiration and nitrogenous compounds produced during protein metabolism are the major excretory products in plants. The main excretory materials formed in plants are: alkaloids, tannins, resins, gums, and organic acids.
- The pressure flow hypothesis helps explain how dissolved sugars move from sugar sources to sugar sinks. When sinks need sugar, the pressure difference between the source and sink causes dissolved sugars to move to the area of need. Excess sugars can be stored in areas such as roots to be used later.
- Cytoplasmic streaming is the cells transport system which moves a cells content around as required. This occurs in the cytoplasm of the cell, the fluid which fills the space between organelles and contains cell solutes. Movement in the cytoplasm is thought to be facilitated by actin-myosin motors.
- Oxygen in the air spaces in the soil dissolves in the film of moisture surrounding soil particles and diffuses into the root hair along a concentration gradient. It diffuses from root hair cells into the cortex where it is used for respiration.
- Some minute pores which are usually, found in leaf for the exchange of gas and transpiration are known as stomata. They are typically found in plant leaves and can also be found in stems and other parts of plants.
- Lenticels are specialized structures located in the felodermis, whose function is to guarantee the entry of oxygen and gas exchange.
- A facultative anaerobe is a microorganism that is capable of switching between both aerobic and anaerobic respiration for producing energy depending on the presence or absence of oxygen in the surrounding environment.
- A facultative aerobe is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent.
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