B2 Part A

Question 1

List the 5 main features of an animal cell

Answer 1

1. Nucleus
2. Cell membrane
3. Ribosomes
4. Cytoplasm
5. Mitochondria

Question 2

Which feature of an animal cell is ‘selectively permeable’? Define this term

Answer 2

The cell membrane is selectively permeable, meaning that it allows certain molecules or ions to pass through it by means of active or passive transport.

Question 3

What are mitochondria?

Answer 3

Sites of aerobic respiration, which allow energy to be released so that the cell can function.

Question 4

What is the purpose of ribosomes?

Answer 4

Ribosomes connect amino acids onto one another in order to make proteins. They are known as protein synthesizers.

Question 5

List the 3 features that are specialist to plant cells and outline what they do

Answer 5

1. The cell wall (made of cellulose) strengthens and supports the cell.
2. Permanent vacuoles contain cell sap (a weak solution of salts and sugars which provide energy)
3. Chloroplasts contain a green substance called chlorophyll, which is where photosynthesis occurs.

Question 6

Draw a diagram of a fungal/yeast cell and finish this sentence: Yeast is a …………… microorganism

Answer 6

Yeast is a single-celled microorganism

Question 7

Draw a bacteria cell (or list the 9 main features)

Answer 7

Question 8

What is the purpose of the flagellum and which two main types of cell have them?

Answer 8

It enables mobility of both bacteria and sperm cells.

Question 9

What is the equation for calculating magnification?

Answer 9

Magnification = size of subject in the image ÷ actual size of subject

Question 10

Which feature of a sperm cell is a cap of enzymes that breaks down the egg wall?

Do sperm cells have mitochondria and a nucleus?

Answer 10

The acrosome is a cap of enzymes that breaks down the egg wall.

Yes, sperm cells have mitrochondria and a haploid nucleus.

Question 11

Why are red blood cells biconcave and why don’t they have a nucleus?

Answer 11

Red blood cells are biconcave because it increases the surface area/volume ratio (bigger surface area). They have no nucleus because this means there is more space for oxygen to attach to the cell.

Question 12

What form of nucleus does a white blood cell have and why?

Answer 12

It has a lobed nucleus so that it is able to control the whole cell and engulf foreign bodies.

Question 13

What type of cell is this? Draw a labelled diagram

Answer 13

Root hair cell

Question 14

What is the purpose of guard cells? Draw a labelled diagram

Answer 14

Guard cells change shape to control gas and water exchange

Question 15

What type of cell is this? Label the diagram

Answer 15

Question 16

What is an egg cells purpose?

Answer 16

To carry the female DNA and nourish a developing embryo in the early stages, for this it contains huge food reserves.

Question 17

What is a tissue?

Answer 17

A collective of specialised cells that perform the same function

Question 18

What is an organ?

Answer 18

An organ is various different tissues working together for the same outcome

Question 19

What is an organ system? Give an example

Answer 19

A series of organs that work in conjunction with one another eg. The digestive system

Question 20

Name the three different types of tissue in the stomach and outline their purpose

Answer 20

Muscular tissue - contracts and shortens to cause movement that churns up the chyme in the stomach

Glandular tissue - excretes substances which assist with digestion of food in the stomach cavity

Epithelial tissue - covers the inside and outside, acting as a protective lining. Often the cells will be columnar so that other types of cell can embed themselves.

Question 21

Label this diagram of the digestive system

Answer 21

Question 22

What is the purpose of

1. Glands (eg. the pancreas and salivary glands)
2. The stomach
3. The liver
4. The small intestine
5. The large intestine

Answer 22

1. Glands produce digestive juices
2. The stomach breaks down and digests food
3. The liver produces bile
4. The small intestine absorbs soluble food molecules
5. The large intestine absorbs water from undigested food, leaving faeces to be excreted from the anus

Question 23

How does bile aid the digestive system?

Answer 23

The enzymes in the small intestine work best in alkaline conditions, but the food is acidic after being in the stomach. Bile is an alkaline substance stored in the gall bladder. It is secreted into the small intestine, where it emulsifies fats and provides a larger surface area in which the lipases can work.

Question 24

What plant life process occursin mesophyll tissue?

Answer 24

Photosynthesis

Question 25

Give the equation for photosynthesis

Answer 25

Carbon Dioxide + Water ⇒ Glucose and Oxygen ⇒ = sunlight and chlorophyll

Question 26

Where does photosynthesis occur in plants?

Answer 26

In the chloroplasts

Question 27

Draw a labelled cross section of a leaf (12 labels in total)

Answer 27

Question 28

Describe the process of photosynthesis in 4 main steps

Answer 28

1. Sunlight is absorbed by chlorophyll (in the chloroplasts) 2. Carbon dioxide diffuses into the leaf and water from the soil reaches cells via the xylem 3. Using energy from the sunlight, the carbon dioxide and water is converted into glucose in the chloroplasts of the leaf 4. Oxygen is released as a by-product

Question 29

What is the purpose of the waxy cuticle of a leaf?

Answer 29

It stops water from escaping and protects it from insect bites

Question 30

Name the two different types of mesophyll layer in a leaf and outline their purpose

Answer 30

Palisade mesophyll layer - second layer of cells (below the upper epidermis), because it is towards the surface of the leaf and palisade cells contain chloroplasts, it is the main sit for photosynthesis. Spongy mesophyll layer - a layer of spongy irregular shaped calles and air space where gas is able to circulate so the plant can absorb it

Question 31

In which part of a leaf would you find the most stomata and what is their function?

Answer 31

The lower epidermis will be covered in tiny holes (with guard cells eitherside) known as stomata, these openings will contract to control gas exchange. Guard cells also contain chloroplasts.

Question 32

Which four factors effect the rate of photosynthesis?

Answer 32

1. Light intensity 2. Volume of carbon dioxide in the atmosphere 3. Temperature 4. Amount of water available

Question 33

What does a limiting factor do to the rate of a reaction?

Answer 33

A limiting factor prevents a reaction happening any faster

Question 34

# Fill in the gaps: At night, .............. is a limiting factor of photosynthesis. In winter it will be the .................. but if it's both warm enough and bright enough, the amount of ................. is usually limiting

Answer 34

At night, **light** is a limiting factor of photosynthesis. In winter it will be the **temperature** but if it's both warm and bright enough, the amount of **carbon dioxide** is usually limiting.

Question 35

Draw and label a rate of photosynthesis/light intensity graph and annotate

Answer 35

Question 36

Which other limiting factor of photosynthesis creates a graph of the same shape as light intensity? Draw and annotate if it helps

Answer 36

Concentration/volume of carbon dioxide

Question 37

Draw and annotate the graph of rate of photosynthesis/temperature. At what temperature do enzymes in the leaf tend to denature and be destroyed?

Answer 37

45 °C

Question 38

How might a famer artificially create ideal conditions for photosynthesis in order to make their crops grow at the fastest rate posssible?

Answer 38

Grow them in a greenhouse

Question 39

List the five different ways plant use the glucose made in photosynthesis

Answer 39

1. For respiration 2. Converting into celulose to make cell walls 3. Creating proteins 4. For storing in seeds 5. To store as starch

Question 40

What is glucose combined with in order to make proteins?

Answer 40

Glucose is combined with nitrate ions from the soil to make amino acids, which can be turned into proteins.

Question 41

Why is starch better for storing than glucose? Which plants store a lot of it underground so the plant can grow from it the following spring?

Answer 41

Starch is insoluble, wheareas if glucose was stored it would absorb lots of water and cause the plant to swell. Potato and Parsnip plants (we eat the swollen storage units)

Question 42

What is glucose converted into in order for it to be stored in seeds?

Answer 42

Lipids (fats and oils)

Question 43

Which environmental factors affect where an organism will live? (5)

Answer 43

* Temperature * Availability of water * Availability of oxygen and carbon dioxide * Availability of nutrients * Amount of light

Question 44

Outline two methods by which you can study the distribution of an organism

Answer 44

1. Measure how common an organism is in two sample areas (eg. by using quadrats and calculating the mean number of organisms in each) and compare them 2. Study how the distribution changes across an area (eg. by placing quadrats along a transect)

Question 45

How would you work out the population size of an organism in a sample area? eg. In 800m² with a mean average of 22 daisies per m², what is the total population?

Answer 45

Work out the mean number of organisms per m² and then multiply the mean by the total area of the sample size 22 x 800 = 17,600

Question 46

When collecting environmental data what two things must you be aware of?

Answer 46

* Reliability (repeatable and reproducable) - take a large sample size and use random samples * Validity - control all the variables