Answer:
The correct answer will be option-D.
Explanation:
Calcium plays an important role in muscle contraction as they are released from the sarcoplasmic reticulum after they receive electric impulse.
Calcium triggers the muscle contraction cycle as these calcium ions bind to the troponin-tropomyosin complex. This binding exposes the myosin-binding site on the actin on which high energy myosin binds and cross-bridge is formed.
This cross-bridge formation causes the contraction of the sarcomere and therefore muscle contracts.
Thus, option-D is the correct answer.
No Nucleus
All members of the kingdom Monera have no nuclei in their cells. All genetic material in moneran cells floats loose in the cytoplasm. In fact, the only parts of the cell that exist in a moneran are the cell wall and the ribosomes. Moneran cell walls are made of peptidoglycan. This is the case for all monerans except for archaebacteria. Monerans also move about using flagella.
Digestion
Monerans digest their food outside of the cell and then absorb the nutrients. Different monerans, however, digest their food in a variety of ways. Some simply generate their own food by making their organic compounds. Others need to feed off of other organic matter, such as decaying material. Some monerans are parasites that feed off of a host and others create a symbiotic relationship with another organism. According to Thinkquest.com, monerans are separated into different classifications by how they feed.
Other Characteristics
Monerans reproduce by both sexual conjugation or asexual binary fission. Circulation is done by diffusion, which is similar to the way they digest. Monerans all breathe differently. Some cannot survive without oxygen while some die if exposed to oxygen. Monerans come in three different shapes: spiral, rod-shaped or spherical. In order to protect themselves, most Monerans are surrounded by a capsule of polysaccharides that keeps them from drying out and acts as protection against other harmful cells.
Answer:
In mendelian inheritance, the alleles for a gene show normal dominant-recessive relationship. Chromosomes also show crossover due to which new random combination of traits is possible in the offspring. This crossover takes place between homologous chromosomes during meiosis I.
Organellar DNA like the ones present in mitochondria and chloroplast do not follow mendelian inheritance because unlike nuclear chromosomes they do not have cross over events. There is no orderly segregation of alleles during meiosis. Traits controlled by them are usually inherited as it is and usually it is from the maternal parent because paternal gamete like sperm does not contain mitochondria.
The cell cycle or cell-division cycle is the series of events that take place in a cell leading to its division and duplication of its DNA (DNA replication) to produce two daughter cells. In bacteria, which lack a cell nucleus, the cell cycle is divided into the B, C, and D periods. The B period extends from the end of cell division to the beginning of DNA replication.
