Arthropoda and molluscs have open circulatory systems - meaning haemolymph (Their equivalent to blood) directly bathes the tissue, and isn't enclosed in blood vessels, as seen in a closed blood system, as in humans for example.
Dorsal means back as in the back area. Example~ Many dolphins have a pronounced beak and all have a central dorsal fin and sharp teeth for feeding, mainly on squid and fish.
Answer:
Electrons
Explanation:
According to the modern atomic theory, atoms are made-up of smaller subatomic particles in the nucleus. The nucleus contains two types of subatomic particles, protons and neutrons. The protons have a positively electrical charge and the neutrons have no charge. The electrons have a negative electrical charge and are able to move around the nucleus. An atom usually contains an equal number of positively charged protons and negatively charged electrons. This makes the atom itself electrically neutral. The electrons exist at different energy levels, called shells, around the nucleus where they revolve freely in a constant motion.
Answer: Orbit
Explanation: The Earth’s axis being in orbit means that the Earth is in different positions around the sun at different points in time, causing day and night.
basically it means the connection between 2 bases
A is complementary to U in RNA
T is complementary to A in DNA
U to A
G to C/C to G