Multi cellular organisms are composed of many cells whereas unicellular organisms are composed of single cell. Multicellularity is indeed a progressive attribute of evolution where cells form tissue which forms organ and then organ system and finally an organism. Both multi cellular and unicellular organisms has advantages and disadvantages of their own. One of the main disadvantage of multi cellular organisms is that due to such a complex composition and functioning they require a large amount of energy for their maintenance and survival. Different organs and system require a huge amount of energy when it comes to comparison with unicellular organisms. A large amount of energy is also wasted in all these life processes. Though multi cellular organisms can survive in a variety of environmental conditions but then also their survival is difficult than any unicellular organism.
Answer:
The respiratory epithelium in trachea and bronchi is pseudostratified and primarily consists of three main cell types – cilia cells, goblet cells, and basal cells. The ciliated cells are located across the apical surface and facilitate the movement of mucus across the airway tract.
The correct answer is A. Apoptosis is regulated cell death/suicide, not accidental.
The atmosphere transfers heat energy and moisture across the Earth. Incoming solar radiation (insolation) is redistributed from areas in which there is a surplus of heat (the equator) to areas where there is a heat deficit (the North and South Pole). This is achieved through a series of atmospheric cells: the Hadley cell, the Ferrel cell and the Polar cell (Figure 2). These operate in a similar way to, and indeed interact with, the ocean conveyor.
For example, as the oceans at low latitudes are heated, water evaporates and is transported poleward as water vapour. This warm air eventually cools and subsides. Changes in temperature and CO2 concentrations can lead to: changes in the size of atmospheric cells (in particular, the Hadley cell is susceptible to these alterations); warming in the troposphere; and disproportionately strong warming in Arctic regions. The strong interactions between ocean and atmospheric dynamics, and the significant feedback mechanisms between them, mean that climate researchers must consider these Earth components as interlinked systems. The necessity to assess ocean-atmospheric changes at the global scale has implications for the way in which research is conducted. It is only by integrating palaeo evidence of past changes, with present day monitoring, and projected models,
