Answer:
A forest ecosystem can support a limited number of bears because bears are the supreme predators of their ecosystem and very few animals can hunt bears so nature by supporting a limited number of bear populations supports a balanced number of population of its prey like insects, fishes, deer.
Another reason for the limited population of bear is that bear occupies the highest trophic level in the ecosystem so according to 10% law of energy transfer, it will get very less energy from its food so it needs to eat more.
Therefore the population of bears is limited because the environment can not meet the energy requirement of many bears so a forest ecosystem can support a limited number of bears.
50 percent of the offspring would be expected to have the ability to roll their tongues If a heterozygous male is crossed with a homozygous recessive female.
Explanation:
Information given:
the ability to roll tongue is dominant, the genotype would be RR, Rr
the inability to roll tongue is recessive trait the genotype = rr
Given that heterozygous male is crossed with homozygous recessive female, the genotype is
Rr X rr
Punnet square shows that:
R r
r Rr rr
r Rr rr The genotype ratio is 1:1
phenotype ratio is 1:1
There are chances of 50 % offspring having the ability to roll their tongues as they are heterozygous and have the dominant allele for rolling of tongues.
The correct answer is:
D
.Villi in the small intestine have thin-walled capillaries to make the absorption of nutrients more efficient.
Explanation:
The small intestines are well adjusted for absorbing nutrients during digestion by being very long, having villi and microvilli that enlarge surface area, using muscular contractions to move and mix food, and raising and housing digestive enzymes and bile that aid the breakdown of food. The inner surface of the small intestine is not flat but thrown into circular folds, which not only enhance surface area but aid in preparing the ingesta by acting as baffles. Villi: the mucosa makes multitudes of ridges which project into the lumen and are satisfied with epithelial cells.
Answer:
The correct answer is 3: "<em>High levels of Ca2+ are expected to be found </em><em>within the sarcoplasmic reticulum</em>".
Explanation:
Muscular contraction is a highly regulated process that depends on free calcium concentration in the cytoplasm. Amounts of cytoplasmic calcium are regulated by <u>sarcoplasmic reticulum</u> that functions as a storage of the ion.
When a nerve impulse reaches the membrane of a muscle fiber, through acetylcholine release, the membrane depolarizes producing the entrance of calcium from <u>extracellular space</u>. The impulse is transmitted along the membrane to the sarcoplasmic reticulum, from where calcium is released. At this point, <em>tropomyosin is obstructing binding sites for myosin on the thin filament</em>. The calcium channel in the sarcoplasmic reticulum controls the ion release, that activates and regulates muscle contraction, by increasing its cytoplasmic levels. When <em>calcium binds to the troponin C</em>, <em>the troponin T alters the tropomyosin by moving it and then unblocks the binding sites,</em> making possible the formation of <em>cross-bridges between actin and myosin filaments.</em> When myosin binds to the uncovered actin-binding sites, ATP is transformed into ADP and inorganic phosphate.
Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
The statement is - False.
The vinegaroon has became very similar in appearance to the scorpions, by having similar body, similar proportions to certain species, having a whip tail. The whip tail though is not a mimic for the scorpion's pincher claws, but instead, it is a mimic of the scorpion's stinger. This adaptation of the vinegaroon has the purpose to fend of the predators by making them think that it is actually a scorpion and that they will get a nasty poisonous sting. This type of adaptations by mimicking certain traits of more dangerous species can be found in lot of animals from all shapes and sizes.
