Which alga is used by space travellers as a food supplement?

In oogamy,fertilization involves

Kelp (branched form) and Sargassum (filamentous form) belong to:

In which of the following is the embryo absent?

Some characters of algae are given below:
$a.$ Floridean starch
$b.$ Sulphated phycocolloids in cell wall
$c.$ Alginic acid
$d.$ Trumpet hypha
$e.$ Haplodiplontic life cycle
$f.$ Isomorphic alternation of generation
$g.$ Fucoxanthin
$h.$ Phycoerythrin
$i.$ Zygotic meiosis
$j.$ Two anterior flagella
Which of the given set of characters belongs to $Laminaria$?

'Pond silk' is the common name of