Membrane phospholipids
have hydrophobic heads that face the centre of the membrane and are shielded from water.
have hydrophilic tails that face outward and are exposed to water.
are able to drift about in the plasma membrane
remain fluid because they are tightly packed against one another.
A hypothesis is
the same as a theory
a proposed explanation for a set of observations
an explanatory idea that is broad in scope and supported by a large body of evidence
a widely accepted idea about a phenomenon
Which level in the hierarchy shown is a community?
all environments on earth supporting life
savannah
all organisms in the savannah
group of cheetahs
Which of the following organisms belongs to the group represented in Box 1?
giraffe
tree
decomposing bacteria
leopard
Which of the following statements regarding a common cellular activity is false?
cells respond to the environment
cells develop and maintain complex organization
cells regulate their internal environment
new cells are derived from cellular components like organelles
You notice that over the past month, many students on campus have started wearing a new style of school sweatshirt. You think to yourself that perhaps the bookstore has recently started selling this new sweatshirt style. This prediction is an example of
an experimental question.
a type of observation.
a hypothesis.
an experiment.
Which of the following is a trace element in the human body?
nitrogen
zinc
oxygen
hydrogen
What is the atomic mass of an atom that has 6 protons, 6 neutrons, and 6 electrons?
6
8
12
18
A hydrogen atom has one electron. How many covalent bonds can hydrogen form?
one covalent bond
two covalent bonds
four covalent bonds
no covalent bonds
Household ammonia has a pH of 12; household bleach has a pH of 13. Which of the following statements about them is true?
Both of these substances are strong acids.
The ammonia has 10 times as many OH- ions as the bleach.
The ammonia has 10 times as many H+ ions as the bleach.
A solution that could buffer the bleach and ammonia would remove excess OH- ions.
________ are weak bonds that are not strong enough to hold atoms together to form molecules but are strong enough to form bonds within and around large molecules.
ionic
covalent
polar covalent
hydrogen bonds
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