Heart rate is controlled by the two branches of the autonomic (involuntary) nervous system. The sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The sympathetic nervous system (SNS) releases the hormones (catecholamines - epinephrine and norepinephrine) to accelerate the heart rate.
secondary statement makes a seem correct
A leaf is made up of many layers and is surrounded by two. Upper epidermis, mesophyll, bundle sheath, vein, mesophyll, lower epidermis, and guard cells.
Explanation:
charles darwin proposed thoery of natural selection.he had collected imnumerable specimens of plant and animals.he published concept survival of fittest. while explaining he says that There is always competition for food.only those organism survive which shows adptations in various reasons. it thoery of natural selection.
There are some objections,
1. natural selection is not only factor responsible for evolution.
2. darwin did not mention uesful and useless modifications.
3. There is no explanation about slow and abrupt changes
Answer:
The faster the particles are moving, the more energy they have. Why is convection more important than conduction in the troposphere? The air doesn't conduct heat well so only the first few meters of the troposphere are heated with conduction
