Q: Evidence for the presence of what on mars makes scientists think that life might have existed there in the past? Choices: - gas - plasma - air - water A:
water

(Question)
Q: What did volcanic gases help to form on earth? Choices: - water - plants - rocks - atmosphere A:
(Answer)
atmosphere

Ques: Q: What happens when when the immune system does not work properly? Choices: - anemia - diabetes - stroke - immunodeficiency A:
Ans: immunodeficiency

(Q).
Q: Acids can also react with metals, and when they do they produce what? Choices: - alloys - potassium gas - rust - hydrogen gas A:
(A).
hydrogen gas

Ques:Q: What are modified leaves that bear sporangia? Choices: - spines - neutrophils - sporozoans - sporophylls A:

Ans:sporophylls

Ques:Q: What are named for their "spiny skin"? Choices: - arachnids - reptiles - amphibians - echinoderms A:

Ans:
echinoderms