Key Concepts In Bioligy

Question 1

A plant cell, a prokaryotic cell, or a eukaryotic cell

Answer 1

Eukaryotic cell

Question 2

In which sub cellular structures, do most of the reactions for respiration take place

Answer 2

Mitochondria

Question 3

Which sub cellular structure maintains the internal pressure in a Plant cell

Answer 3

Vacuole

Question 4

Describe the main similarities and differences between a bacterial cell and a plant cell

Answer 4

Similarities: both have a cell membrane, a cell wall, cytoplasm and ribosomes

differences: plant cells have chloroplasts and mitochondria, but bacteria do not, the chromosomes of a plant cell are contained within the nucleus where as bacteria have chromosomal DNA that floats freely in the cytoplasm, bacterial cells may also contain small loops of extra DNA called plasmids

Question 5

Where are ciliated epithelial cells found

Answer 5

On the surface of organs

Question 6

Give two functions of an egg cell

Answer 6

To carry the female DNA and to provide nutrients to the embryo in early stages

Question 7

Why do sperm cells contain a large number of mitochondria?

Answer 7

Provide energy (from respiration) needed to swim to the egg

Question 8

Why is it important that egg and sperm cells are haploid?

Answer 8

So that when an egg cell and a sperm cell nucleus combine at fertilization the resulting cell will have the right number of chromosomes (haploid cells only have half the chromosomes of a normal body cell)

Question 9

Describe how ciliated epithelial cells are adapted for moving substances

Answer 9

They have Celia, which beat to move substances in one direction along the surface

Question 10

Why does the structure of an eggs cell membrane change after fertilization?

Answer 10

To stop any more sperm getting in ,making sure that the offspring end up with the right amount of DNA

Question 11

What is the purpose of the fine adjustment knob on a light microscope?

Answer 11

It’s used to focus the lens until a clear image of what’s on the slide appears

Question 12

True or false? electron microscope’s have a smaller magnification than light microscope’s, but they have a higher resolution than light microscope’s

Answer 12

False

Question 13

Describe how you would put a cover slip onto a specimen on a slide, so that it’s ready to be viewed under a light microscope

Answer 13

The cover slip should be placed at one end of the specimen, and held at an angle with the mounted needle. It should then be carefully lowered onto the slide and pressed down gently, so that no air bubbles are trapped under.

Question 14

How has electron microscopy increased our understanding of cells?

Answer 14

The high magnification and high resolution has allowed biologists to see very small structures in detail like the internal structure of mitochondria and chloroplasts. This has allowed biologists to better understand how cells work, and give us a greater understanding of the role of sub cellular structures

Question 15

Is a pico meter smaller or larger than a nanometer

Answer 15

Smaller

Question 16

What is the formula to calculate the microscope’s total magnification?

Answer 16

Image size = actual size X magnification

Magnification = image size/actual size

Image size = magnification/actual size

Question 17

Why might a student want to estimate the size of a protist as well as calculating it with a Calculator?

Answer 17

To ensure the answer they get with a Calculator is sensible

Question 18

How do you enzymes affect the rate of Reaction

Answer 18

Enzymes increase the rate of reaction and act like a biological Catalyst

Question 19

What is an active site of an enzyme?

Answer 19

The part of the enzyme which joins onto its substrate to catalyze the reaction

Question 20

True or false? enzymes usually only work with one substrate

Answer 20

True

Question 21

What are some variables that affect the rate Rate of an enzyme catalyzed reaction

Answer 21

Temperature, pH and substrate concentration

Question 22

What happens to an enzyme when it’s denatured?

Answer 22

Some of the bonds holding the enzyme together a break, and the shape of its active site changes. This means that the substrate won’t fit so the enzyme can no longer catalyze a reaction anymore.

Question 23

True or false? pH is the dependent variable in an experiment investigating how pH affect enzyme activity

Answer 23

False

Question 24

In an experiment investigating how pH affects Emily’s activity, what would you use to test for the presence of starch?

Answer 24

Iodine solution

Question 25

A student is investigating the effect of pH on the rate of amylase activity. Suggest how the student could control the temperature of the amylase and starch solution during the experiment.

Answer 25

The student could put a test tube containing the solution in a beaker of water over a Bunsen burner and use a thermometer to help keep the water at a constant temperature. Alternatively, the student could use an electric water bath.

Question 26

The student uses continuous sampling to record how long it takes for the amylase to break down all of the starch .what is continuous sampling?

Answer 26

Continue sampling is When Lots of samples are taken at regular intervals over a particular time Period.

Question 27

Which type of molecule are proteins broken down into

Answer 27

Amino acids

Question 28

What type of enzyme breaks down proteins?

Answer 28

Proteases

Question 29

Vikash is eating rice, which contains a lot of the carbohydrate starch. name the type of enzyme that will break down the starch during digestion

Answer 29

It will be broken down into carbohydrases

Question 30

How are carbohydrates synthesized?

Answer 30

Simple sugars are joined together to form carbohydrates in a process catalyzed by enzymes

Question 31

Why is it important that organisms are able to break down big molecules into smaller molecules?

Answer 31

Big molecules are unable to pass through the wall of the digestive system and can’t be absorbed into the bloodstream. Small molecules can pass through and be absorbed, which means they can pass through and be absorbed , which means they can then pass into cells and be used for growth and other life processes.

Question 32

True or false? oxygen entering the blood from the lungs is an example of osmosis

Answer 32

False. It happens by diffusion osmosis, involves the movement of water molecules

Question 33

What type of membrane is needed for osmosis to happen?

Answer 33

A partially permeable membrane

Question 34

When plants lose water, they start to wilt explain why most plants will wilt if the soil they are growing and is flooded with salty sea water

Answer 34

Due to the seawater, having a high concentration of salt, the water concentration in the soil will be lower than in the plant. This means water will move by osmosis causing the plant to lose water and wilt

Question 35

Oxygen diffuses from the bloodstream into muscles. during exercise oxygen is used up in the muscles faster than when a person is at rest suggest how the rate of oxygen diffusion might affect when a person is running, compared to when they are sitting down

Answer 35

Diffusion rate will be greater when the person is running compared to when the person is sitting down this means that there will be a lower concentration of oxygen in the muscles as it is used up quicker meaning there will be a greater concentration gradient, and so a faster rate of diffusion

Question 36

How does water concentration change as solute concentration increases

Answer 36

The water concentration of a solution decreases as the solute concentration increases

Question 37

How would the mass of a potato cylinder change if you put it in a solution that has the same water concentration as the fluid inside the potato

Answer 37

There would be no change in mass of the potato cylinder

Question 38

Yas has two potato cylinders. The fluid inside the potato cells has the same concentration. She weighss the two cylinders and places them into different beakers one of pure water the other with glucose solution. after 24 hours she removed the cylinders, dries them and measures their final mass. Explain how the mass of each potato cylinder will have changed after 24 hours.

Answer 38

The mass of the cylinder in pure water will have increased because the water will have moved by osmosis from an area of higher water concentrate in the pure water to an area of lower concentration in the potato. the mass of the cylinder in the glucose solution will have decreased as the water will have moved by osmosis from the area of higher water concentration in the potato to an area of low concentration, the glucose solution

Question 39

If during an experiment of investigating the water movement by osmosis, the potato cylinders weren’t dried properly, so the excess water added to the mass of the potato was added how could this error be reduced?

Answer 39

Repeat the experiment and calculate the mean percentage change in mass