Most enzymes in the human body work best at
around 37°C – body temperature
. At lower temperatures, they will still work but much more slowly. Similarly, enzymes can only function in a certain pH range (acidic/alkaline). Their preference depends on where they are found in the body.
Which letter indicates the part of the graph that represents the carrying capacity?
Carrying capacity is the maximum number of individuals of a particular species that a specific environment can support. It’s represented by the
letter K
.
Which substance usually passes in the greatest amount through the placenta from the blood of the fetus to the blood of the mother?
Carbon dioxide
is produced abundantly in the fetus, and the P
CO2
of fetal blood is higher than maternal blood. Carbon dioxide therefore diffuses from fetal blood, through the placenta, into the maternal circulation, and is disposed of by expiration from the mother’s lungs.
When S marcescens a bacterium is grown in a refrigerator?
>_3. Wher S marcescens a bacterium is grown in a refrigerator, it produces
red-colored colonies
However, if the bacterium is grown at room temperature, the colonies are white.
Why is it difficult for demographers to determine the Earth’s carrying capacity?
However, it is
very difficult
for ecologists to calculate human carrying capacity. Humans are a complex species. We do not reproduce, consume resources, and interact with our living environment uniformly.
What crosses the placental barrier?
Drugs that have
low molecular weight, lipid (fat) solubility, nonpolarity
, and no protein binding properties will quickly and easily cross the placenta. Alcohol, for example, readily reaches the embryo in fairly high concentrations.
Why is the blood of the mother separated from the blood of the fetus?
The placenta produces a number of hormones that are needed during pregnancy, such as lactogen, oestrogen and progesterone. It keeps the mother’s blood separate from the baby’s blood
to protect the baby against infections
.
What substances Cannot pass through the placenta?
Whether a substance may pass through the placenta between mother and fetus depends on its molecular size, shape, and charge. The substances not likely to pass in significant amounts include
bacteria, heparin, sIgA, and IgM
. Most antigens are small whereas IgM is a large molecule.
Which condition would most likely result in a human body being unable to defend itself against pathogens and cancerous cells?
. Which condition would most likely result in a human body being unable to defend itself against pathogens and cancerous cells?
a genetic tendency toward a disorder such as diabetes 1
.
Which substances play an important role in communication?
Neurotransmitters
play a critical role in neural communication, influencing everything from involuntary movements to learning to mood.
Which are abiotic factors most responsible for the increase in the mass of the plant?
Temperature and moisture
are important influences on plant production (primary productivity) and the amount of organic matter available as food (net primary productivity).
What happens when carrying capacity is reached?
If a population exceeds carrying capacity,
the ecosystem may become unsuitable for the species to survive
. If the population exceeds the carrying capacity for a long period of time, resources may be completely depleted. Populations may die off if all of the resources are exhausted.
What is Earth’s human carrying capacity?
Many scientists think Earth has a maximum carrying capacity of
9 billion to 10 billion people
. One such scientist, the eminent Harvard University sociobiologist Edward O. Wilson, bases his estimate on calculations of the Earth’s available resources.
Is carrying capacity a fixed state?
The
carrying capacity for any given area is not fixed
. It can be altered by technology and resource management practices, but mostly it is changed for the worse by pressures which accompany a population increase [1]. A major symptom of reduction in carrying capacity is the reduction of bioproductivity.
Which drug does not cross blood placental barrier?
Most drugs with MW < 500 Da cross the placenta, and most drugs with MW > 1000 Da do not cross the placenta (ex.
heparin, protamine, insulin
). Neither succinylcholine (highly ionized) or non-depolarizing NMBDs (high molecular weights) cross the placenta.
What are the features of placental barrier?
The placental barrier between mother and fetus is the “leakiest” barrier and is
a very poor block to chemicals
. The placenta is composed of several layers of cells acting as a barrier for the diffusion of substances between the maternal and fetal circulatory systems.
