Biology Year 9 test - 1.1

What does every organism (except viruses) contain one or more of?

cells

In plant cells, there is a cell wall, chloroplast and a large permanent vacuole. What about animal cells?

They have no cell wall or chloroplasts present, or a permanent vacuole.

What does the cell membrane do?

Controls substances entering and leaving the cell

What does the cytoplasm do?

Its a gel-like substance where most of the chemical reactions happen

What is the function of the nucleus?

The nucleus contains chromosomes which carry genetic information and control the activities of the cell

What does the cell wall do?

It contains cellulose - supports the plant's structure

What is the chloroplast's function?

Absorbs light for photosynthesis

What does the vacuole do?

It contains cell sap and helps maintain the shape of the cell

What does cell sap contain?

A dilute solution of sugars and mineral salts

What is the mitochondria the site of?

aerobic respiration

What chemical is used to examine animal and plant cells?

Methylene blue or iodine

What is the calculation for magnification?

Magnification \= size of image ÷ size of real object

What is the maximum light microscopes can magnify?

1000x

How do you achieve total magnification?

It is achieved by the multiplication of the power of the eyepiece lens

What do electron microscopes use?

It uses a beam of electrons instead of light

What is the maximum electron microscopes can magnify?

up to 50,000,000x

What is a disadvantage of electron microscopes?

You can only study dead cells

What did electron microscopes allow scientists to discover?

Internal structures of cells

What does an iodine stain do?

It makes the nucleus more obvious and stains any starch present

What does methylene blue stain?

It stains acidic parts of the cells blue and make the nucleus more obvious

Which stain is most commonly used to stain plant cells?

Iodine

Which stain is most commonly used to prepare slides of animal cells and bacteria?

Methylene blue

What are the simplest forms of living organisms called? (only one cell)

Unicellular organisms

What are organisms that consist of many cells called?

multicellular

How many cells are humans made up of?

34 to 37 trillion

Give an example of a specialised cell

muscle cells

What are tissue cells?

Groups of similar cells with a similar function

Give an example of tissue cells

Muscle cells contract and therefore shorten

What are organ cells?

Several tissues performing specific functions, eg. the heart pumps blood

What is an organ system?

A group of organs working together to perform a particular function, eg. the circulatory system carries substances around the body

What do molecules of liquids and gases do?

Collide against each other all the time

What passes through the cell membrane by diffusion?

Oxygen and carbon dioxide

Molecules diffuse from an area of high concentration to an area of...?

low concentration

Does the process of diffusion require energy?

No

In diffusion, all liquid and gas molecules have ..... energy.

kinetic energy - they are constantly moving and mixing

The greater the difference in concentration between two areas...

the faster the rate diffusion happens

As the temperature increases...

the rate of diffusion increases (molecules have more kinetic energy)

If there is high pressure, the molecules...

will quickly move from the area of high pressure to low pressure

Where does every substance that enters or leaves the cell cross?

cell membrane

What kind of membrane is the cell membrane?

selectively permeable membrane

What does the term 'selectively permeable membrane' mean?

The membrane allows certain molecules to pass through, but not others.

What is an example of a small molecule?

water

What is an example of a large molecule?

minerals, sugars

What can you use to model how the cell membrane?

visking tubing

Define aerobic respiration

Aerobic respiration is a process that happens in cells when oxygen is available. It is a series of reactions controlled by enzymes.

When does respiration occur?

all the time

What is the equation for aerobic respiration?

glucose + oxygen --\> carbon dioxide + water + energy (ATP)

Define anaerobic respiration.

the release of a relatively small amount of energy by the breakdown of food substances in the absence of oxygen

Anaerobic respiration is less efficient than aerobic respiration because..

less ATP is produce per molecule of glucose (glucose molecule isn't completely broken down)

What is the equation for anaerobic respiation?

Glucose -\> lactic acid

Name an advantage of anaerobic respiration

Muscles can release energy for a short period when not enough oxygen is available, e.g. 100m sprints.

Name 2 disadvantages of anaerobic respiration

• Lactic acid is released which is harmful to the body. In the muscles, lactic acid can cause pain (cramp).

• It is not suitable for activities that require energy release over a long period of time, e.g. a long-distance run.

What is an oxygen debt?

The amount of extra oxygen your body needs to react with the build up of lactic acid and remove it from the cells

It is a good measure of fitness to see how quickly you can recover from an 'oxygen debt'.

A fit person can:

o Breathe in a greater volume of air.

o Produce less lactic acid,

o Break down lactic acid faster.

Why do large organisms require a complex respiratory system?

To obtain sufficient volume of oxygen to maintain a high level of aerobic respiration + remove an equivalent volume of waste carbon dioxide.

What is the function of the respiratory system?

• get oxygen into the blood

• remove carbon dioxide from the blood.

What are alveoli covered by on the outside?

blood capillaries

What diffuses across the walls of the alveoli (from the air into the blood)?

Oxygen

What goes from the blood into the air?

Carbon dioxide

How are alveoli adapted for gas exchange?

• large surface area

• good blood supply

• thin - short diffusion pathway

• moist - dissolve gases

What is the difference between inspired air and expired air?

Inspired air is breathed in and expired air is breathed out

What does the body absorb from inspired air?

Oxygen

What does the body add to expired air?

Carbon dioxide and water vapour

What does expired air have more than inspired air?

Carbon dioxide and water vapour

What does inspired air have more than expired air?

Oxygen

How do you test for carbon dioxide?

Bubble limewater through a straw - it goes cloudy

What gas stays the same during breathing?

Nitrogen

Why does the air need to be cleaned before it reaches the alveoli?

The alveoli are very delicate

What does the mucus trap?

dust and other small particles (bacteria)

What moves the mucus upward?

cilia + in a wave like motion

What happens to the mucus pushed?

You swallow it and acid in your stomach destroys any bacteria

What is a trend?

A trend is a pattern or change over a long period of time

How long does tobacco smoke paralyse cillia in the trachea and bronchi for?

about an hour after the cigarette is smoked

What irritates lungs, then clogs mucus?

Dry dust and chemicals

What happens if mucus builds up and becomes infected?

It can cause bronchitis

\___ damages alveolar walls

Coughing

What happens when the alveolar walls are damaged?

It reduces surface area for gas exchange and results in the sufferer being short of oxygen

What does tar do?

It collects in the lungs as the smoke cools and paralyses cilia

What does carbon monoxide do?

It binds permanently to haemoglobin, and prevents oxygen from being delivered to tissue as much as 15%

What are the effects of nicotine?

Increased alertness and concentration, appetite suppression, and vasocontriction. It is also very addictive

What does tar contain?

carcinogens

\__ of lung cancers are thought to be caused by smoking

90%

What are the statistics for death from lung cancer?

1 in 10 moderate smokers, and 1 in 5 heavy smokers die from lung cancer

What is the function of the respiratory system?

supply the body with oxygen and dispose of carbon dioxide

Why do large organisms need to obtain a sufficient volume of oxygen?

to maintain a high level of aerobic respiration

What does chlorophyll do?

absorbs light energy

What is the equation for photosynthesis?

Carbon dioxide + water -\> glucose + oxygen

What can be used to measure the rate of photosynthetic activity?