BBC Knowledge AUGUST 2017

&Answers

Questions

14

HOW DO THEY

MAKE SPACESUITS

AIRTIGHT?`

HOW DO MICROBEADS

AFFECT FISH?

Spacesuits are made of lots of different

layers that each protect the astronaut

from a different aspect of the outside

environment. Only the innermost layer –

known as the bladder – is airtight.

It’s made of urethane-coated nylon that

has machine-welded seams. The gloves

are attached using airtight bearings that

lock into place but still allow the hand to

be rotated. These use precisely machined

aluminium and titanium couplings with

Teflon coatings for lubrication to prevent

the metals cold-welding together in

the vacuum of space. Astronauts also

breathe pure oxygen so the suit can

be inflated at less than a third of normal

atmospheric pressure. Even so,

spacesuits aren’t perfectly airtight.

NASA allows the suits used on the ISS

to leak up to 100ml of air per minute. LV

There’s no doubt that fish and other aquatic animals eat

plastic fragments (under 5mm). These include the

‘microbeads’ that are added to toiletries and household

products, as well as fibres washed from synthetic clothing.

A recent study found three-quarters of flatfish in the River

Thames have eaten microplastics. Even deep-sea animals

have synthetic fibres in their guts. The impacts of this are

complex. Some animals suffer from blocked digestive tracts,

leading to starvation. Another concern is poisoning from

microplastics coated in toxic chemicals. There’s still much

we don’t know about exactly how plastics and toxins

accumulate in food webs. HS

CAN PLANTS GET CANCER?

Yes. Crown galls are a kind of plant cancer, caused by the bacterium

Agrobacterium tumefaciens. This causes uncontrolled growth of plant

cells around the infection, just like a tumour. Other tumours can be

triggered by fungi or physical damage. But plant cells are anchored

in place by the cell walls, so plant cancers never spread far or

metastasise to other tissues. LV

Astronauts breathe

oxygen before and during

a spacewalk to rid their bodies

of nitrogen, which could

form dangerous bubbles

Agrobacterium

tumefaciens in action

Plastic microbeads (orange

spheres) in a facial scrub