What of the following describes how an organism responds to external stimuli
1.a person yawns when oxygen is low in the lungs
2.the pupil of the eye gets larger when exposed to darker conditions
3.a dog eats food when its hungary
4.a woman drinks water when she is thirsty

What came first egg or chicken? and is tomato a vegetable or a fruit?

You have 2 plants of the same type and same size, same amount of leaves. one of them is put inside the house and the other one is put in the balcony. you water them saturday, one plant with 200 ml and the other with 400 ml of water. which one of your plants need less water? explain.

Which image shows labeled organelles that are present only in plant cells?