Athletes and Muscles fibres

During Heavy physical work or strenuous exercise the demand for oxygen increases many fold. The oxygen does not diffuse into the skeletal muscle fibres at the required rate. Skeletal muscle fibres contain an oxygen storing pigment myoglobin.

 There are two types of muscle fibres :
1. Red (dark) 
2.White (pale)

Red muscle fibers are richer in myoglobin content than the white muscle fibres. Therefore, red fibres can utilize the oxygen stored in myoglobin to continue energy production over prolonged periods by aerobic oxidation of glucose.This enables them to perform sustained work over a long period.

On the contratory, white fibres produce the energy needed for very fast and severe work by glycolysis, mainly because sufficednt oxygen is not  immediately available for them for such work.

But white muscles accumulate lactic acid and get fatigued in a short time. Thus,athletes with a higher proportion of red fibres in their muscles are physiologically better equipped for sustained events such as cycling, running or swimming over long distances. Athletes with a higher proportion of white fibres in their muscles are equiped for fast, intense but short activities such as sprint, short put etc.     

Structure of Chromosome

Are you confused between following ? 1.kinetochore and centromere 2.p arm and q arm 3.sister cromatides and non sister chromatides. I am sure followinig pictures will clear all your confusion

Recombinant DNA Technology

Reproduction - Double Fertilization

Ecology And Environment - Population Intractions

Mutualism : Both the interacting species are benefited.

Ex.
1. Lichens = Fungi + Algae
2. Mycorrhizae = fungi + Roots of higher plants
3. Ophrys :

Ophrys is a large group of orchids from the alliance Orchis in the subtribe Orchidinae. These plants are remarkable in that they successfully reproduce through pseudocopulation, that is, their flowers mimic female insects to such a degree that amorous males are fooled into mating with the flowers, thereby pollinating them.
They are referred to as the "Bee orchids" due to the flowers of some species resemblance to the furry bodies of bees and other insects. 
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Predation : In ecology, predation describes a biological interaction where a predator (an organism that is hunting) feeds on its prey .

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Parasitism : Parasitism is a non-mutual relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host.

Ex. Brood parasitism : Is the phenomenon in which one parasitic bird species lays its eggs in the nest of another bird species.

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Commensalism : Is an interaction in which one species is benefited while the other species is neither benefited nor harmed.
Ex. Orchids grow as epiphytes on mango trees or other fruit trees. (orchids are benefited by getting shelter,while the tree is neither benefited nor harm.

Ex. 

Cattle egrets and livestock

An example of commensalism: cattle egrets foraging in fields among cattle or other livestock. As cattle, horses and other livestock graze on the field, they cause movements that stir up various insects. As the insects are stirred up, the cattle egrets following the livestock catch and feed upon them. The egrets benefit from this relationship because the livestock have helped them find their meals, while the livestock are typically unaffected by it.

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Competition : Harmfull for both.

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Amensalism : One is harmed and other is neither harmed nor benefited.

Ex. The black walnut secretes a chemical from its roots that harms neighboring plants, an example of amensalism.

Reproduction - Fertilization and cleavage

In embryology, cleavage is the division of cells in the early embryo. The zygotes of many species undergo rapid cell cycles with no significant growth, producing a cluster of cells the same size as the original zygote. The different cells derived from cleavage are called blastomeres and form a compact mass called the morula. Cleavage ends with the formation of the blastula.