The meteorite was probably 1<span>0 to 15 km (6.2 to 9.3 mi) wide</span> and affected the entire planet through a proces called "impact winter". As the name suggests, an impact winter is a period of low temperature produced by a huge cloud of ash and dust that blocks sunlight. Since sunlight is essential for plants to survive, if the sun rays are blocked by this cloud, all animals that depend on those plants (including dinosaurs) will die. The meteorite could have created such a cloud upon hitting the earth.
Physical exercise preserves bone mass. Measurements of bone biomarkers may reflect the events in bone during exercise. Fifteen healthy, well-trained individuals (7 men and 8 women) performed a running test for 21 min until exhaustion. Venous blood samples were drawn before and 30 min after the exercise to measure the levels of osteocalcin, the carboxyterminal propeptide of type I procollagen (PICP) and the carboxyterminal cross-linked telopeptide of type I collagen (ICTP). After exercise, the women had a marked increase in serum osteocalcin concentrations (from 7.5±5.0 μg/1 to 11.5±3.0 μg/1), whereas the level was unaffected in the men (from 14.5±3.0 μg/1 to 13.5±4.6 μg/l). In the men there was a marked increase in PICP (from 240±47 μg/1 to 268±56 μg/1) that was not seen in the women (from 244±70 μg/1 to 253±60 μg/1). In neither group did ICTP levels change. In conclusion, significant responses were seen in PICP and osteocalcin during exercise, indicating that such measurements may be valuable for the further delineation of the effects of physical activity on bone. Furthermore, the different responses in men and women point to interesting areas for future studies.
There is a 1:4 chance of getting JjQq. The parent JjQq can produce four genotypes: JQ, Jq, jQ, and jq. the parent JJQq can produce two genotypes: JQ and Jq. When we do a punnett square:
JJQQ, JJQq, JjQQ, JjQq,
JJQq, JJqq, JjQq, and Jjqq
There are two JjQq.
Two out of eight is one out of four.
Answer:
The fact that most eukaryotes reproduce sexually is evidence of its evolutionary success. In many animals, it is actually the only mode of reproduction. The genetic diversity of sexually-produced offspring is thought to give species a better chance of surviving in an unpredictable or changing environment.
The correct answer is: A checkpoint will be activated if the spindle does not attach to a kinetochore.
Prokaryotes, do not undergo mitosis (like eukaryotes) and therefore have no need for a mitotic spindle. Prokaryotes also don’ t have checkpoints foor the regulation of cell division.
Normal eukaryotic cells (unlike cancer cells), move through the cell cycle in a regulated way in order to make sure that cells don't divide under conditions that are unfavorable for them. Information about their own internal state (nutrients, signal molecules, DNA integrity) is signal to go or not to go through the cell division. Because of that there are few checkpoints in the cell cycle at which the cell examines the signals and makes a “decision”. The major checkpoints are:
• The G1- the first point at which it must choose, once it passes the G1 checkpoint the cell enters S phase
• The G2-the cell checks DNA integrity and checks if replication is done well.
• The spindle checkpoint-at the transition from metaphase to anaphase.
