Which of these is most like a closed system that does not allow transfers in or out of the system?
a planet earth
b a coral reef
c a school
d the human heart

Planet Earth  is most like a closed system that does not allow transfers in or out of the system

A. Planet Earth

Explanation:

In a closed system, there is no exchange of mass. However, the energy might get exchanged. The exchange of mass and energy depends upon the property of the membrane or the boundary of the substance or an object.

The Earth is basically a closed framework; it acquires huge amount of energy from the Sun yet the exchange of matter with the outside is just about zero. Material streams between stores or sinks along pathways, or motions.

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explanation:

fertilization, pictured in figure 24.23a is the process in which gametes (an egg and sperm) fuse to form a zygote. the egg and sperm each contain one set of chromosomes. to ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. in mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida. when a sperm binds to the zona pellucida, a series of biochemical events, called the acrosomal reactions, take place. in placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane, as illustrated in figure 24.23b. the fusion of these two membranes creates an opening through which the sperm nucleus is transferred into the ovum. the nuclear membranes of the egg and sperm break down and the two haploid genomes condense to form a diploid genome.

explanation: