Ammonoids are good as index fossils because of the following characteristics;
<span>1.
</span>Their abundance and vast distribution across most shallow
marine waters during the periods
<span>2.
</span>They have easily recognizable
features, such as shells and the highly crenulated and complex suture, that are well preserved in rocks
<span>3.
</span>Their rapid
evolution that can assist determine changes and variations in the then environment
Answer:
D
Explanation:
It is often like this: cell->tissue->organ->system
The answer is <span>B. In both oogenesis and spermatogenesis, the cells become haploid after meiosis I.
Gametogenesis is a process in which gametes are produced. Oogenesis is a process in which egg cells are produced and spermatogenesis is a process in which sperm cells are produced. Both processes include meiosis.
Original diploid cell (primary oocyte or spermatogonium) has 46 chromosomes. After meiosis I, there are two haploid cells. After meiosis II, there are 4 haploid cells because meiosis II is similar to mitosis. The difference between spermatogenesis and oogenesis is that those 4 cells after meiosis II in spermatogenesis are all sperm cells, and in oogenesis only one of them is egg cell.</span>
Answer:
Reflex action is the sudden uncontrolled reaction towards a certain stimuli eg response to hot iron
Reflex arc is the path taken by reflex action to a certain stimuli
Diagram depends to
Receptor(eg skin), receptor nerve(sensory neurone),centre reflex arc(spinal cord most of reflex action) they met relay neurone, motor neurone and ends at reflexor (eg muscle)
