<span>Refraction happens when there</span> is a bending of path of a light wave as it
passes across the boundary separating two media and the degree of bending is
determined in part by the total change in velocity as the light<span> passes from one medium to the other. In
addition, the change in speed experienced by a
wave when it changes medium can result in a number of beautiful optical effects. </span>
<span>Damming a river has a variety of effects on the freshwater ecosystem, more than just altering the flow from A to B. Dams create calm bodies of water, changing overall temperature regimes and sediment transport, leading to conditions which tend to favour generalist species. Loss of specialist species, particularly endemics, changes the community structure and leads to biotic homogenization. A dam will withhold sediment in the reservoir, not just decreasing the amount of substrate available to local freshwater species, but even impacting diadromous, estuarine and marine species much further downstream. The competition between resident species for food and breeding sites will increase as damming isolates populations, and perhaps more importantly, damming completely restricts migratory fish species. Isolation may lead to decreases in genetic diversity and therefore puts species at greater risk from disease. All of these effects may be exacerbated by changes in the surrounding land use. Overall, damming river flow will lead to both a loss of native species, but also an increase in exotic species which are more likely to become established in degraded habitats. For this reason, dams are one of the greatest global threats to freshwater biodiversity.</span>
<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:
C)Both proteins bind ATP and F-actin
*C option is not mentioned* there is a flaw in the question
Explanation:
Two families of motor proteins, kinesin and dynein, transport membrane-bounded vesicles, proteins, and organelles along microtubules. Nearly all kinesins move cargo toward the (+) end of microtubules (anterograde transport), whereas dyneins transport cargo toward the (−) end (retrograde transport).While
both the protiens have globular ATP-binding heads that function as the motor domain and interact with the microtubules.
Answer: c. alluvial fan.
A wide sloping deposit of sediment formed where a stream leaves a mountain range is called an alluvial fan. An alluvial fan is the deposition of sediment on a landform like mountain. It forms as an open fan or cone of sediment. The sediments are left by natural drainage system like river on the landform.
There are two types of alluvial fans.
1. Debris dominated: These includes viscous mixture of water, mud, gravel along with woody debris. This transfer large boulders of landform soil.
2. Floodwater dominated: Water will spill in the alluvial fan in the form of thin sheets. This can transfer fine particles of landform soil.
