Greenhouse gases are naturally occurring gases that are also produced as a result of human consumption, such as the burning of fossil fuels. They are essential to life in that a gas such as carbon dioxide (Co2) is essential to photosynthesis and the production of oxygen which helps to sustain life. However, the levels of greenhouse gases are far outreaching their natural limits and are having a negative impact on human and animal life.
Most of the changes in an ecosystem are gradual. The gradual changes taking place in the ecosystem allows the organisms to evolve slowly. As a result of evolution, the species can adapt and survive in the changing environment.
Also, the gradual changes allow speciation and other ecological advantages. Any sudden changes in the ecosystem can be drastic, as all the organisms would not be able to adapt the sudden change, as a result they will extinct.
Answer:
a. True
b. True
c. False
d. True
e. False
f. False
g. True
Explanation:
The homeotic genes refer to evolutionarily conserved genes that modulate the development of different structures in organisms of the same groups (in this case, plants). Moreover, homeobox genes are genes that encode transcription factors involved in the regulation of development in eukaryotic organisms. The knotted1 (<em>kn1</em>) gene is a plant homeobox gene is a member of the <em>kn1</em> homeobox (<em>knox</em>) gene family, which is responsible for maintaining indeterminacy and preventing cellular differentiation. In maize, <em>kn1</em> plays a key role in maintaining the cells of the shoot apical meristem in an undifferentiated state, being mainly expressed in shoot meristems during postembryonic stages of shoot development. It has been observed that maize mutant plants where <em>kn1</em> is ectopically expressed (i.e., in tissues in which this gene is not normally expressed) exhibit proximal-distal patterning defects.
False
A single-celled organism doesn't need a circulatory system as human do. Since they are singular, they can interact with their environment directly. Unlike them, a multicellular organism like a human has a part where their cells can't get oxygen or food directly, thus need to be supplied by the circulatory system. Some of the cells also well differentiated so it only accept a certain processed food.