The first heart sound, "lubb," is caused by the . The first heart sound, "lubb," is caused by the . closing of the atrioventricular valves regurgitation of the atrioventricular valves closing of the semilunar valves blood flowing into the ventricles

Living cells cannot use heat to provide the activation energy for biochemical reactions because which choice(s) complete the sentence correctly? a) answer choice ii. eliminate b) answer choices ii and iv. c) answer choice iii and iv. d) all answers can complete the sentence.

Getting out of bed is the first goal i tackle each day. 2several small goals are achieved by me as the day progresses. 3when i am riding the bus home or walking the dog, i think about the bigger goals i have for my life. which statement correctly describes the verb tense, aspect, and voice in this paragraph? a.sentences 1 and 2 contain present progressive verbs. sentence 3 contains both present progressive and simple present verbs. sentence 2 uses passive voice. b.sentences 1 and 2 contain simple present verbs. sentence 3 contains present progressive verbs. all three sentences use active voice. c.sentences 1 and 2 contain present progressive verbs. sentence 3 contains simple present verbs. all three sentences use active voice. d.sentences 1 and 2 contain simple present verbs. sentence 3 contains both present progressive and simple present verbs. sentence 2 uses passive voice.

Interactions between organisms and their environment impact the organism’s overall population. the jaguar panthera onca is the largest cat in north america. it is found in areas across the southwest, including arizona, new mexico, and texas. it is a carnivore that has powerful jaws and sharp teeth and preys on fish, turtles, tapirs, and many smaller mammals. which shows the relationship between the jaguar and turtles?