biology 1 - 2022

Name one type of cell in a potato plant that does not contain chloroplasts

root hair cell

What is the independent variable in the osmosis potato practical?

concentration of solution

In the potato osmosis practical, why would a potato decrease in mass?

water moves out of potato
via osmosis
as the solution in the potato is less concentrated as the outside

Name a disease caused by a fungus

Rose black spot

Where is protein digested in the human digestive system?

stomach

Which chemical could be used to test if burgers contain protein?

biuret reagant

Onion microscope practical:
Why use a thin layer of onion epidermis?
Why use iodine solution?
Why lower the cover slip at an angle?

to help see individual cells
to stain the parts of the cells, more clear
to prevent air bubbles

What should you do when drawing the cells from the onion microscope practical?

include a scale
label cell parts

Onion cells can be seen using an electron microscope. Give two ways onion cells would look different when seen using an electron microscope.

• sub-cellular structures can be seen

• higher resolution

Hornets are insects that sting other animals and cause pain. Hornet moths do not sting other animals. Suggest how mimicry helps the hornet moth survive.

it looks like a hornet
so other animals are deceived
and do not eat it

Explain why a tree might die if the roots of the tree are damaged. (6)

• less absorption of water so less photosynthesis

• fewer magnesium ions so less chlorophyll produced

• phloem damaged, so less transport of sugars

• xylem damaged, so less transport of water

• less anchorage

Name the process by which stem cells then form specialised cells

differentiation

Describe two differences between the transpiration stream and translocation.

• transpiration involves xylem, translocation involves phloem

• transpiration transports water, translocation transports dissolved sugars

Which environmental conditions would cause the rate of transpiration to be greatest in a plant?

warm with low humidity

Suggest the advantages of a plant adjusting the width of its stomata based on the time of day.

• at night, there is less light for photosynthesis

• closing it prevents water loss

• open wide at midday because max light intensity for photosynthesis

• take in the most carbon dioxide for photosynthesis

Explain how the adjusting the stomata would help the plant to survive in low atmospheric carbon dioxide.

stomata are open wider and for longer

allows it to take in more carbon dioxide for photosynthesis

Organism B exchanges gases with the environment directly through its skin.

Organism D exchanges gases with the environment using its respiratory system.

Explain why organism D requires a respiratory system, but organism B does not.

D has a smaller surface area to volume ratio

so diffusion distance is too large to meet demands of cells

Describe how the alveoli and the villi are adapted to increase absorption.

• both large surface area to maximise diffusion

• both thin walls to reduce diffusion distance

• villi contains a lot of mitochondria for active transport

• villi have micro villi to increase surface area

Explain how a vaccine for HIV could work to prevent a person developing HIV infection.

• monoclonal antibody binds to the HIV antigen

• they bind to all the antigens

• so HIV cannot bind to human cells