Answer:
1. False
2. True
3. True
4. False
Explanation:
In mammals, the contraction of the heart muscle is caused by pacemaker cells localized within the sinoatrial (SA) node. These cells rhythmically generate slow electrically-induced action potentials due to their slow rate of depolarization. The pacemaker cells generate the action potentials that propagate through the heart and trigger the contraction of myocyte cells (i.e., myocytes simply conduct the action potential waves). The slow depolarization of pacemaker cells occurs during diastole, i.e., during the period of relaxation of the heart muscle.
The exoskeleton of an arthropod is chitin.
two strands of DNA are held together by weak hydrogen bonds.
I think it is because in the ocean the plankton produces most of the oxygen which is used by aquatic plants and plankton is a primary producer known as autotrops.
Answer :— Physical properties of plastic samples collected by SEA in the Atlantic Ocean indicate the collected material is made of HDPE (high density polyethylene), LDPE (low density polyethylene), and PP (polypropylene), which are used to make common household items such as milk jugs, plastic bags, and drinking straws.Plastics and polystyrene foam (Styrofoam) comprise 90% of all marine debris, with single-use food and beverage containers being one of the most common items found in ocean and coastal surveys.
Hope you understand
