Answer:
a. heart development.
Explanation:
As the third week of fetal development starts, the process of formation of blood vessels begins. Also, the splanchnic mesoderm in the head end of the embryo forms heart on days 18 and 19. Since it develops heart, this part of the mesodermal cells is called the cardiogenic area. The underlying endoderm sends the induction signals to these mesodermal cells to form a pair of endocardial tubes that gradually develop into a single primitive heart tube.
This primitive heart begins to beat by the end of the third week of development. Therefore, any drug that affects fetal development during the first 20 days of the pregnancy might affect the development of the heart.
Answer:
Ribosomes are the site where <em>proteins </em>are produced. Amino acids are coded for by triplet bases in RNA called <em>codons</em>. Hope this helps
Answer:
B. The burning of fossil fuels released greenhouse gases into the atmosphere causing the planet to get warm.
Explanation:
Take for example - you touching something sharp and instantly moving your hand away.
Sensory neurons in your fingers detect the external stimuli of the sharp object and send a nerve impulse to the spinal cord (does not reach brain) and is sent back to a motor neurone - attached to an effector that moves the muscle and moves the hand away. This is a rapid reflex action and involuntary.
1) Chordata=A chordate is an animal of the phylum Chordata. All chordates possess 5 synapomorphies, or primary characteristics, at some point during their larval or adulthood stages that distinguish them from all other taxa
2) Vertebrates=vertebrate, also called Craniata, any animal of the subphylum Vertebrata, the predominant subphylum of the phylum Chordata. The vertebrates are also characterized by a muscular system consisting primarily of bilaterally paired masses and a central nervous system partly enclosed within the backbone.
3)Invertebrates=Invertebrates are animals that neither possess nor develop a vertebral column, derived from the notochord. This includes all animals apart from the chordate subphylum Vertebrata. Familiar examples of invertebrates include arthropods, mollusks, annelid, and cnidarians.
4) Poikilothermic animals=A poikilotherm is an animal whose internal temperature varies considerably. Poikilotherms have to survive and adapt to environmental stress.
5) Homeothermic animals=The term homeothermic refers to the warm-blooded animals which have constant and relatively higher temperature. They are animals which can maintain their internal body temperature. Complete answer: Homeothermic animals are warm-blooded and maintain a constant body temperature, for example birds and mammals.
6) Oviparous= producing young by means of eggs which are hatched after they have been laid by the parent, as in birds.
7)Vivaparous=bringing forth live young which have developed inside the body of the parent
Sorry if it's incorrect
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