Answer:
Your heart changes its rate depending on the activity, so that it can carry blood to your muscles, and therefore it needs to beat stronger if you are performing some exercise, or not so strong if you are sleeping, for example.
Explanation:
Your heart is continuously beating to keep blood circulating throughout your body.
So, here it is why your heart changes its rate: Its rate changes depending on your activity level; it is lower while you are asleep and at rest and higher while you exercise to supply your muscles with enough freshly oxygenated blood to keep the functioning at a high level.
And how: depending on your activity level, your heart has to pump enough blood to your muscles. Blood carries needed oxygen and other nutrients. Muscles need more blood sugar than any other tissue especially when working hard. To supply your muscles with oxygen your heart needs to beat faster, and this builds up your heart muscles.
Plants roots display positive gravitropism which means they grow in the direction of gravity
There are microorganisms that are able to live in extreme environments under adverse conditions of pH, temperature and salinity. These microorganisms are classified as extremophiles. Within the group of extremophiles there are halophilic bacteria, which are those capable of living in extremely saline environments.
One biological factor that all living things are subject to suffer from is osmotic pressure. Halophilic microorganisms have developed mechanisms to adapt to saline environments where osmotic pressure acts with great intensity on individuals. These bacteria change the chemical composition of their membranes and also accumulate osmoprotective compounds in their cytoplasm to compensate for osmotic stress.
RAMIREZ, N; SANDOVAL, AH y SERRANO, JA. Las bacterias halófilas y sus aplicaciones biotecnológicas. Rev. Soc. Ven. Microbiol. [online]. 2004, vol.24, n.1-2 [citado 2019-09-22], pp. 12-23 . Disponible en: <http://ve.scielo.org/scielo.php?script=sci_arttext&pid=S1315-25562004000100004&lng=es&nrm=iso>. ISSN 1315-2556.
Answer:
a. Centromere
A centromere is a specialised DNA sequence of a chromosome that links pair of sister chromarids (a dyad)
