Answer: The surface of an epithelial cell which lies closest to its blood supply is called as the Basal surface.
Epithelial cell is primarily composed of two surface-
1) Apical surface- It is exposed to the environment and lies towards the lumen or internal organ cavity.
2) Basal/ Basolateral surface- It is not exposed to the environment. It lies interiorly and attached to the basement membrane via integrin.
Epithelial cells do not have own blood supply. For obtaining nutrients, they are dependent on the blood capillaries which are present in the nearby tissues. For accomplishing this, the basal surface of epithelial cell plays an essential role. The nutrients from blood enters basal surface via basement membrane which is a selectively permeable membrane.
Thus, basal surface of epithelial cells lies closest to the blood supply.
Answer is (C) The birds of Bocas del Toro evolved from immigrants from the mainland.
A scientist studying tropical birds in Panama notices that the environment of the islands of Bocas del Toro is more like the environment of small islands in Honduras than that of the mainland of Panama. She hypothesizes that birds in Bocas del Toro will share more traits with birds on the islands in Honduras than they will with birds on mainland Panama. She records her observations of bird species in all three locations and concludes that the species on Bocas del Toro are more similar to species on the nearby mainland. The similarity in the traits can be because the birds of Bocas del Toro evolved from immigrants from the mainland.
Answer: Option A) Double-stranded DNA
Explanation:
First, the presence of thymine infers that the genome is DNA.
Then, to determine whether it is single or double stranded, we check if the sum of all nitrogenous bases is equal to 100%
A + C + G + T = 100%
28% + 35% + 20% + 17% = 100%
Since all bases makes 100%, we can conclude that the genome is a double stranded DNA
