Answer:
Robert Hazen’s studied enviromental and biological processes that might have been critical for life, and also for the formation of approximately two-thirds of Earth's mineral species (see Hazen et al., 2008; Gonzalez & Richards 2020)
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Explanation:
Hazen provided evidence about how first organic molecules were generated on the primitive earth millions of years ago. He observed that high-pressure hydrothermal vents may provide food for underwater ecosystems. It represents a piece of critical evidence on the origin of life.
You can read these articles that are certainly clarifying in the description of his experiments and discoveries:
1- Hazen, R. M., Papineau, D., Bleeker, W., Downs, R. T., Ferry, J. M., McCoy, T. J., ... & Yang, H. (2008). Mineral evolution. American Mineralogist, 93(11-12), 1693-1720.
2- Gonzalez, G., & Richards, J. W. (2020). The privileged planet: how our place in the cosmos is designed for discovery. Gateway Editions.
Answer:
Here are the answers:
a. 4 Cell determination as an issue in the *rest is missing*
b. 4 They assumed that different ways of separating an embryo into two parts would be equivalent as far as the fate of the two parts was concerned.
c. 4 I and III only
Explanation:
The passage demonstrates the importance of two factors in the development of an embryo: cleavage planes of division of embryonic cells and cell differentiation.
Cleavage Planes:
Cleavage basically refers to the division of the zygote into a large number of cells called blastomeres. Cleavage planes are geometrical lines or orientations along which cleavage takes place. Since, all embryonic cells are the precursors of some type of body cells, the cleavage planes determine if the cells are adequate for growth and development.
Cell Differentiation:
Cell differentiation is the transition of an undifferentiated cell into a specialized one. For example, stem cells are undifferentiated cells that develop into progenitor cells that mature into a specific cell lineage. For an embryo to regenerate, the presence of adequate embryonic stem cells is crucial. Embryonic stem cells are present in abundance before the gastrulation phase of embryonic development, after which they rapidly start differentiating.
The OECD found that the responsiveness of housing supply to demand in the UK was the weakest among developed countries, due in large part to green belt policies. The green belt concept was first introduced for London in 1938 before the 1947 Town and Country Planning Act enabled local authorities to designate the status themselves. The policy was introduced to contain urban sprawl following huge post-war housing developments, and expanded greatly between 1951 and 1964. Since 1979, the green belt has doubled to cover 13 per cent of land in England (while only 2.3 per cent is covered by buildings).
