MRM Science--Photosynthesis, Respiration & Cell DIvision
Terms in this set (93)
Every living thing needs energy. Plants and certain other obtain their energy from what source to make their own food?
What is photosynthesis?
the process by which a cell captures energy in sunlight and uses it to make food
Nearly all living things, directly or indirectly, get their energy captured by sunlight during what process?
Where does grass obtain its energy?
directly from the sunlight because it makes its own food during photosynthesis
Where does a zebra get its energy?
indirectly, from the energy stored in the grass it eats.
what do you call an organism that makes its own food through photosynthesis?
What do you call an animal that cannot make its own food?
Is a zebra an autotroph or a heterotroph?
Many heterotrophs obtain food by eating other organisms. How does a heterotroph like fungi get their food?
they absorb it from other organisms.
What material inside a leaf captures light energy?
During photosynthesis, plants and some other organisms use energy from the sun to convert carbon dioxide and water into what two substances?
oxygen and sugars.
What are the two stages of photosynthesis?
Capturing the sun's energy and producing sugars.
In the first stage of photosynthesis, where does the energy-capturing process mostly occur?
in the leaves
What is a chloroplast?
Green organelles inside plant cells.
Where does the green color in chloroplasts come from?
what are pigments?
colored chemical compounds that absorb light
What is the main photosynthetic pigment in chloroplasts called?
It is Chlorophyll
In the second stage of photosynthesis, what substance capture light energy?
The substance is Chlorophyll
What two raw materials does the cell need to produce sugars during the second stage of photosynthesis?
carbon dioxide and water
Where does CO2 enter the plant?
Through a small opening on the undersides of the leaves called the STOMATA.
What is the singular of stomata?
Where does the water and CO2 move to once its in the leaves?
Where do the series of complex chemical reactions take place during the second stage of photosynthesis?
Inside the chloroplasts.
What powers the chemical reactions that take place during the second stage of photosynthesis get their energy?
from the energy captured during the first stage of photosynthesis
Besides six-carbon sugars, what is the other product of photosynthesis?
Where does the oxygen exit the leaf?
through the stomata
What happens to the sugar produced in photosynthesis?
Plants use some for food, some is broken down by the cell to release energy to carry out the plant's functions, some are stored for later use and others are converted to other compounds, such as cellulose.
When you eat food from plants, such as potatoes or carrots, you are eating what?
the plant's stored energy
In the photosynthesis equation, what do you call the arrow that connects the 6 molecules of CO2 and the six H2O molecules on the left side with the one molecule of sugar and six molecules of oxygen on the right side?
it means "yields" and is labeled Light Energy in this equation.
Before food can provide your body with energy, where must it first pass?
Through your digestive system where it is broken down into small molecules.
Where do the small molecules that your digestive system has made go?
Into your bloodstream where it travels to the cells of your body.
What is respiration?
The process by which cells obtain energy from glucose, which is a type of sugar that your body converts from food.
During photosynthesis, plants capture energy from the sunlight and save it in what form?
Carbohydrates, including sugars and starches
"Respiration" has two meanings. One is "breathing" and the other respiration process that takes place inside cells is sometimes called what?
What is the first stage of respiration?
Takes place in the cytoplasm of the organism's cell where molecules of glucose are broken down into smaller molecules.
Is oxygen involved in the first stage of respiration?
no, and only a small amount of energy is released.
Where does the second stage of respiration take place?
In the mitochondria, where small molecules are broken down into even smaller molecules.
Is oxygen involved in the second stage of respiration?
yes, and a lot of energy is released which is why the mitochondria are sometimes called the "powerhouses" of the cell.
What are two other products of respiration?
carbon dioxide and water
What do you take in when you breathe in and what leaves your body when you breathe out?
you take in oxygen and breathe out carbon dioxide and some water
Describe the Respiration Equation.
Sugar + oxygen yields carbon dioxide + water + energy
What are the raw materials for respiration?
sugar and oxygen
Where does the glucose in the cells of animals and other organisms come from?
the food they consume
Where does the oxygen used in respiration come from?
the air or water surrounding the organism
Describe the photosynthesis equation.
Carbon dioxide + water yields (through light energy) a sugar + oxygen
How is the Photosynthesis equation the same or different than the Respiration equation?
they are opposite processes.
During photosynthesis, CO2 and H2O are used to produce sugars and oxygen. During respiration, the sugar glucose and oxygen are used to produce what?
CO2 and H2O
What purpose do the two processes, Photosynthesis and Respiration, serve?
They form the cycle that keeps the levels of oxygen and CO2 fairly constant in Earth's atmosphere.
Through what process do organisms living where there is no oxygen obtain their energy?
What is fermentation?
a (low) energy-releasing process that does not require oxygen
What type of fermentation occurs when yeast and some other single-celled organism break down sugars?
alcoholic fermentation because alcohol is one of the products along with CO2 and a small amount of energy
Who uses alcoholic fermentation?
baker, because the air pockets created by CO2 causes bread to rise, and brewers because CO2 is the source of bubbles in beer and sparkling wine.
What is one product of the type of fermentation that takes place at times in your body?
Why do we get lactic acid when we exert ourselves?
Our muscle cells use up the oxygen faster than it could be replaced. The lack of oxygen causes fermentation which produces lactic acid that makes our muscles feel weak and sore.
How does a pumpkin grow in size?
By increasing both the size and number of its cells.
What do you call the regular growth and division that cells undergo?
During the cell cycle, a cell grows, prepares for division, and divides into two new cells which are called what?
daughter cells, each of which begins the process again
What are the three stages of the cell cycle?
Interphase, mitosis and cytokinesis
Which stage of the cell cycle is the period before cell division?
The first stage: Interphase, when the cell grows, makes a copy of its DNA and prepares to divide into two cells
During the growing part of interphase, the cell grows to its full size and produces what?
the structure it needs. For example, the cell makes new ribosomes and produces enzymes, and makes copies of both mitochondria and chloroplasts.
In what stage of the cell cycle does a cell make an exact copy of its DNA in its nucleus through a process called Replication?
What does DNA hold?
all the information that the cell needs to carry out its functions.
Once the DNA has been replicated, what happens next?
preparation for cell division begins
What is stage two of the cell cycle?
What happens during Mitosis?
The cell's nucleus divides into two new nuclei and one copy of the DNA is distributed into each of the two daughter cells.
There are four parts of mitosis. Name them.
Prophase, metaphase, anaphase and telophase.
The threadlike chromatin in the nucleus condenses to form double-rod structures called chromosomes during what phase of the mitosis?
In chromosomes, how are each of the two rods (in the double-rod structure) alike?
they are identical, an exact copy of the other.
What is each rod of a chromosome called?
What do you call the structure that holds together the two rods of a chromosome?
What happens to the chromatids (rods of the chromosome) as it progresses through the next three phases of mitosis?
the chromatids separate from each other and move to opposite ends of the cell. Then two nuclei form around the chromatids at the two ends of the cell.
If chromosomes are formed during stage one of mitosis, or prophase, what happens during stage two of mitosis, or Metaphase?
The chromosomes line up across the center of the cell and each chromosome attaches to a spindle fiber at its centromere.
What do you call stage three of Mitosis?
what happens during anaphase?
the centromeres split, the two chromatids separate and the cell stretches out as the opposite ends are pushed apart.
During the fourth stage of mitosis, Telophase, what happens?
The chromosomes begin to stretch out and lose their rodlike appearance. A new nuclear envelope forms around each region of the chromosomes.
What is the third phase of the cell cycle?
What happens during the third stage of the cell cycle?
During cytokinesis (which starts about the same time as telophase), the process of cell division is completed. The cytoplasm divides and the organelles are distributed into each of the two new cells.
What is the result of the completion of cytokinesis?
Two new cells, or daughter cells, have formed. Each has the same number of chromosomes as the original parent cell.
When does the cell cycle begin again?
At the end of cytokinesis each cell enters interphase and the cell cycle begins again
How is cytokinesis different in animal versus plant cells?
In animal cells, the cell membrane squeezes together around the middle of the cell. The cytoplasm pinches into two cells and each daughter cell gets about half of the organelles. In plant cells, its rigid walls cannot squeeze together so a cell plate forms across the middle of the cell. The cell plate gradually develops into new cells membranes between the two daughter cells and new walls from around the cell membranes.
During what phase of mitosis does cytokinesis begin?
Who figured out the structure of DNA in 1953?
James Watson and Francis Crick
Whose 1952 x-ray photographs helped the scientists who figured out the structure of DNA?
What does a DNA molecule resemble?
a twisted ladder
The two sides of the DNA ladder are made up of two kinds of alternating molecules. What are they?
A sugar called deoxyribose and phosphates
Each rung of the DNA ladder is made up of a pair of molecules called what?
DNA has four kinds of nitrogen bases. What are they?
adenine, thymine, guanine and cytosine. Commonly referred to as : A, T, G, C
What nitrogen base does A (adenine) pair with only?
Guanine (G) only pairs with which nitrogen base?
What is the key to understanding how DNA replication occurs?
The pairing of nitrogen bases.
When does DNA replication begin?
When two sides of the DNA molecule unwind and separate (like a zipper unzipping).
What happens once the DNA molecule begins to unzip?
the nitrogen bases that are floating in the nucleus pair up with the bases on each half of the DNA molecule.
How do we know that each new DNA molecule exactly matches the order in the original DNA molecule?
Because of the way in which the nitrogen bases pair with one another. A always pairs with T and G always pairs with C.
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