1. B
2. C
I hope this helped!
By the availability of food in plain open. If the main source of food for a certain bird species would be hidden safely in small and hard-to-reach places, then the bird beak would look differently over successive generations, compared to those where food would be easily found on the open.
As your body gets older, it is less able to produce vital nutrients naturally, so it is recommended that adults take multi vitamins, to help offset the loss in vitamins and minerals.
Answer:
The answer is that NE injection has inhibitory effects on the paraventricular nucleus VPN.
Explanation:
It can be said that the destruction of the paraventricular nucleus (PVN) would produce a hyperphagia, on the other hand, the injection of norepinephrine (NE) would increase the feeding in the rats. This is because NE injection has inhibitory effects on the paraventricular nucleus. If neuronal activation in the paraventricular nucleus is increased, food intake by rats would be decreased.
Mutation are two types somatic and germ cell mutation...as there is mutation in germ cell it will alter the normal behavior and produce variation !
random fertilization also causes variation as different setup of genes meets with another different...so chances of variation increases !
and third crossing over is in meiosis when chiasmata forms....so in this two homologous chromosome attach to each other and on separation ... some part exchange so leads to variation !
