Answer:
Option A, keystone species
Explanation:
Keystone species are responsible for controlling any species from becoming dominant over all other species. The keystone species are found at the top of all the energy pyramids and food chains.
They control the explosion of population of prey and hence regulate the overall ecological diversity.
Some common example of keystone species is as follows –
Bison, prairie dog, large mammalian predators,
Hence, option A is correct
I’m pretty sure it’s either D or A
Answer:
C the shapes of continents appeared to allow them to fit together
Combination birth control pills work to prevent pregnancy
mainly because the pills constrain a woman’s time of ovulation – or they stop
your ovaries from releasing ovules. Combination
birth pills are taken orally and they are composed of both steroid hormones and
estrogen which can stop ovulation.
Answer:
a. Naked dna
f. nucleosome
e. solenoid
g. loop domain
d. chromatid
c. chromosomes
b. metaphase
Explanation:
The naked DNA consists of the DNA molecule not associated with proteins.
A nucleosome is an octamer of histone proteins (i.e., dimers of H2A, H2B, H3, H4) associated with DNA.
A solenoid is a chromatin fiber consisting of 30 nanometers (nm), it represents the secondary structure of the chromatin.
The chromatin fibers are organized into loops (300 nm) that represent the tertiary structure of the chromatin. These loops enable to package chromosome segments consisting of about 100 kilobases (kb).
The sister chromatids are two identical DNA-based structures that remain joined together by the centromere to form a single chromosome (700 nm).
