<u>Answer:</u>
Recent evidence suggest that feathers evolved from scales and suggest that 'feathers and pycnofibers' could be homologous.
<u>Explanation:</u>
- One of the major difficult issue related to bird evolution is the evolution of feathers.
- Feathers are considered as the most 'complex integumentary structures' which are found in vertebrates.
- Evolutionary developmental biology suggests that the 'planar scale structure' is been modified for developing into feathers by 'splitting' to form web like structures.
- Scales and Feathers consist of 'two distinct form of keratin' so it was thought that 'each type was exclusive skin structure' but recent study suggests that they are developmental expressions of same skin structures.
Answer:
Both ferns and flowering plants produce spores at some point in their life cycles. True
Only ferns have a gametophyte as part of their life cycle. False.
Only flowering plants produce pollen grains. true
Both a tree and a large fern plant are diploid sporophytes. True
Explanation:
Yes, both ferns and flowering plants produce spores in their life cycles. In fern plant, it produce spores on the underside of the leaves whereas in flowering plant, there are two types of spores such as microspores and megaspores. Both ferns and flowering plants have gametophyte as part of their life cycle. Flowering plants produce pollen grains whereas non-flowering plants produce spores to continue their generation. Both tree and large fern plants having diploid sporophytes which is a necessary part of their life cycle.
Answer:
Estrogen and progesterone are both involved in preparing the endometrium for embryo implantation. Estrogen helps to ensure conception by increasing the amount of secretory glands in the uterus. Estrogen also increases blood supply to the endometrium.
Progesterone is crucial for embryo implantation and maintenance of pregnancy. Progesterone also enlarges secretory glands that produce carbohydrates, proteins and mucin that are required for embryo nourishment before implantation. Progesterone stabilizes endometrial muscles to prevent them from contracting during pregnancy.
Explanation:
- Estrogen and progesterone are steroid hormones of the reproductive system. Estrogen helps in conception whereas progesterone maintains pregnancy.
- Estrogen is secreted during the follicular phase of the menstrual cycle that promotes the growth and maturation of follicles in the ovary.
- Estrogen also induces oestrous behavior in females.
- Secreted by the corpus luteum, progesterone is also a steroid hormone, responsible for implantation of the embryo in the uterus.
Answer:
B) Krebs cycle (citric acid cycle)
Explanation:
Glycolysis breaks glucose into two pyruvate molecules. Pyruvate is decarboxylated into acetyl CoA and the reaction occurs in the matrix of mitochondria. In the mitochondrial matrix, acetyl CoA enters Kreb's cycle and is broken down into CO2 and H2O. For one molecule of acetyl CoA, two molecules of CO2 are released as a by-product. Therefore, out of three carbon atoms of pyruvate, two are released as CO2 during Kreb's cycle.
Based on my observations, I can conclude that lithospheric motion of the South American plate with the Nazca plate and the African plate causes the earthquakes to engage nearest to volcanic activity causing it to either erupt the volcano, or increase the damage caused by the volcano.
