Biology Test - 56

The winding movement of the tendril of a climbing plant is an example of thigmotropism.

Thigmotropism is often seen in plants having tendrils. Tendrils are positively thigmotropic which means that they grow towards things they happen to touch. The plants such as peas and glory lily have leaf tendrils that are positively thigmotropic.

Mature-free pollen grains contain starch grains and/or lipid droplets. In some plants, two-celled pollen grains are shed, i.e., pollen grains contain a generative cell and a vegetative cell at anthesis. Other plants shed three-celled pollen grains that contain a vegetative cell and two sperm cells.

Osteoporosis is a bone disease that occurs when the body loses too much bone, makes too little bone, or both. As a result, bones become weak and may break from a fall or, in serious cases, from sneezing or minor bumps. Osteoporosis means “porous bone.” Viewed under a microscope, healthy bone looks like a honeycomb.

Protoplasm of the cell contains water-like substances with dissolved molecules and suspended in them.

The plant cell comprises the outer layer of the cell wall and the protoplasm. Protoplasm of the plant cell is a fluid, similar to water, contains all the molecules in it. It has the organic and inorganic substances that constitute the living the nucleus, cytoplasm, plastids and mitochondria of the cell. Cytoplasm contains all the particles inside the membrane of a cell.

Louis Pasteurdisproved the idea of spontaneous generation was once and for all.

Earlier experiments showed that microorganisms did not form in closed containers. To control for the possibility that the spontaneous generation of life might require fresh air, Pasteur designed flasks with specially curved necks. His results finally laid the hypothesis of spontaneous generation.

TCA cycleis also known as Krebs cycle.

Tricarboxylic acid cycle, (TCA cycle), also called Krebs cycle and citric acid cycle, the second stage of cellular respiration, the three-stage process by which living cells break down organic fuel molecules in the presence of oxygen to harvest the energy they need to grow and divide.

In all organisms except bacteria the TCA cycle is carried out in the matrix of intracellular structures called mitochondria.

Reproduction is the biological process in which the organism gives rise to young ones or offsprings similar to itself.

It is responsible for the continuity of species generation after generation.

The reproduction in which an offspring is produced by a single parent without the fusion of gametes is called asexual reproduction.

The offsprings are exact replica of their parents and genetically identical.

Asexual reproduction is of many types: Sporulation, Fission, Fragmentation. Budding, Plasmotomy, vegetative propagation, Apomixis & Parthenogenesis.

Thereby, the Asexual mode of reproduction is a common feature in amoeba, Hydra & spirogyra.

Orthodox seeds survive to dry or freezing during ex-situ conservation, as opposed to recalcitrant seeds. Orthodox seeds which can be partially dried (up to \(5 \%\) moisture) and can be stored indefinitely at low temperature \(\left(-10^{\circ}\right.\) to \(\left.-20^{\circ} \mathrm{C}\right)\).

Example: Cereals in a seed, the embryo is present in a dormant state. The moisture contents of seeds are kept low \((5-15 \%)\) and they are stored at low temperature \(\left(-10^{\circ} \mathrm{C}\right.\) to \(\left.-20^{\circ} \mathrm{C}\right)\) with a supply of little oxygen.

Thalamusis a major coordinating center for sensory and motor signaling for the cerebrum.

The cerebrum wraps around a structure called the thalamus, which is a major coordinating center for sensory and motor signaling.

To eliminate the nutrient deficiency disease like night-blindness, vitamin A enriched rice called golden rice has been developed. In these transgenic plants genes forβcarotene (a precursor of Vitamin A) were isolated from a flowering plant Daffodil and was inserted through recombinant DNA technology.