Cell Type Dichotomous Key 1a cell has a nucleus and organelles → go to # 2 1b cell has no nucleus or organelles → bacterial cell 2a cell has a cell wall → go to # 3 2b cell has no cell wall → animal cell 3a cell has chloroplasts → plant cell 3b cell has no chloroplasts → fungal cell What type of cell is A? A)animal B)bacterial C)fungal D)plant

Describe the iron sulfide hypothesis and the lipid membrane hypothesis.

Every compound can be represented by a chemical formula. a chemical formula is the set of symbols showing the elements that make up a compound and their proportions. water’s chemical formula is h 2 2 o. that means a molecule of water contains two atoms of hydrogen and one atom of oxygen chemically bonded. a molecule is a group of two or more atoms bonded together. molecules can range in size from two to thousands of atoms. a molecule of a compound is the smallest unit of that compound. every molecule of water has all the physical and chemical properties of water. that’s because every molecule of water is made of the same elements in the same proportions: two hydrogen atoms and one oxygen! which of the following is a true statement? a every molecule of the same compound will have different properties. b every molecule of a compound has the same proportion of elements. c molecules can be physically separated into smaller units of a compound. d molecules cannot be represented by chemical formulae.

Consider the skeleton. which skeletal system is represented by the shaded portion of the skeleton? spongy skeleton compact skeleton axial skeleton appendicular skeleton