What involves a sperm and egg fusing to form a diploid zygote?
Options:
- (A) Leptospirosis
- (B) produce offspring
- (C) allow growth
- (D) sexual reproduction
- (E) metabolic reaction
- (F) peachleaf willow
- (G) rapid expansion
- (H) Plant reproduction
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Let's think first: Fertilization occurs when a sperm and an egg fuse to form a diploid zygote. Sexual reproduction requires formation of gametes, followed by fertilization. Sexual reproduction involves a sperm and egg fusing to form a diploid zygote.... So the answer is [(D)]

Why can amphibians easily absorb toxins?
Options:
- (A) salamanders
- (B) permeable skin
- (C) hydrate their cells
- (D) it needs them
- (E) poisonous frogs
- (F) Pesticides
- (G) cold blooded
- (H) bending light rays
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Let's think first: Amphibians have permeable skin that easily absorbs substances from the environment. Natural Toxins Toxins are poisonous substances from bacterias, plants or animals. Amphibians have permeable skin that can easily absorb toxins from bacterias, plants or animals.... So the answer is [(B)]

_ contribute to soils.
Options:
- (A) Sediment
- (B) Aphids
- (C) cacti
- (D) Roundworms
- (E) Exfoliation
- (F) Amphibians
- (G) Ringworms
- (H) rainfall
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Let's think first: Roundworms make up the phylum Nematoda. Also, nematoda and rotifera are important groups contributing to soils. Roundworms contribute to soils.... So the answer is [(D)]