Answer:
Coal and oil (if there are two answers)
Less expensive source of energy is available.
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The exposure of certain types of radiation
Answer:by being produced in the testes outside the body
Explanation: spermatogenesis is the production of male gamates,the sperm.this process occurs in the seminiferous tubules in the testes.epithelial cells produces the primary spermatocyte which divides to give a secondary spermatocyte.
The secondary spermatocyte divides to form spermatids,which differentiates to form the spermatozoons.
Testis is housed in the scrotal sac.
Sperm production is sensitive to temperature. Too high temperature can cause formation of abnormal cells . As a result the scrotal sac is located outside the body
Answer:
e) Invertebrates lack a nervous system
Explanation:
One of the main characteristics of invertebrates is that they don't have a backbone. Backbones belong to the skeletal system. A totally different story is the nervous system which runs inside the backbone. Although the more complex nervous systems appear in vertebrates the simply fact of having eyes like crabs or insects implies having a nervous system that can control them.
