Problem:OPTIONS:
- exhaling
- Leptospirosis
- hemmhorage
- Acids
- excretion
- glucose
- bacteria
- respiration

Fact 1: Organs of excretion make up the excretory system. Fact 2: Digestive system Excretory system removes waste and toxic substances from blood. Given the two facts above, what removes waste from blood?
****
A: excretion

Problem:OPTIONS:
- density
- forces
- vibration
- death
- illness
- earthquakes
- Leptospirosis
- volume

Fact 1: Chemical bonds form when substances react with one another. Fact 2: Chemical bonds vibrate. Given the two facts above, what does substances reacting with one another cause?
****
A: vibration

Problem:OPTIONS:
- reducing acid rain
- color of dirt
- looseness of dirt or compost
- basic building blocks of life
- biological diversity
- lead in the soil
- Evaporation of water
- a lack of soil

Fact 1: The looseness of soil has a positive impact on a plant 's roots' growth in that soil. Fact 2: To improve soil, add several top-dressings of dirt or compost. Given the two facts above, what has a positive impact on a plant's roots' growth?
****
A: looseness of dirt or compost

Problem:OPTIONS:
- gene flow
- insects
- Earthworms
- glycogen
- Wind
- mitosis
- seeds
- energy

Fact 1: Plant reproduction requires pollination. Fact 2: Insects pollinate plants. Given the two facts above, what helps plants reproduce?
****
A:
insects