Bothroyd hobbled off in their draw at Millwall on Saturday with a hamstring pull just a week after strike-partner Chopra was ruled out for the season.
Cardiff's 17-goal top-scorer will have a scan to determine how much of their promotion push Bothroyd will miss.
But Parkin said: "I'm definitely ready if Jay is not available."
The 6ft 4ins targetman - nicknamed 'The Beast' - replaced Bothroyd in the 27th minute of their thrilling 3-3 draw at The New Den when the England international limped off.
Parkin almost made an immediate impact as he brought the best out of Millwall keeper David Forde just before half-time.
Cardiff's £100,000 signing has scored just once for the Welsh club since his January transfer window move from Preston North End - a stunning 25-yard strike in a 1-1 draw at Norwich City.
Two points from a possible 12 is not good enough really
Cardiff City striker Jon Parkin
The 29-year-old's thunderbolt at Norwich in January was when he was deputising for Bothroyd during a six-week spell on the sidelines with a hamstring tear.
Now Parkin, who has started just two league games since his move to south Wales, is ready to step in for Bothroyd again and help reignite Cardiff's stuttering Premier League promotion charge.
Bothroyd has endured a barren spell of 10 games without a goal while Cardiff suffered their fourth league without a win at Millwall - their worst run of the season.
So Cardiff manager Jones may have dropped Bothroyd for their home game with Derby County on 2 April after the international break - but Bothroyd's absence may now be enforced.
And Parkin is primed to step in for Bothroyd and Chopra to play alongside Craig Bellamy as Cardiff's attack aim to fire Jones' men back in the automatic promotion race.
"It will be nice to get a bit more playing time and the more I play, the sharper I will become," said Parkin.
"Two points from a possible 12 is not good enough really but other teams are dropping points so hopefully we can start kicking on."
Cardiff remain in fourth in the Championship table - four points behind Norwich City, who occupy the last automatic promotion spot - despite their mini-slump.
Derby's visit to the Cardiff City Stadium is the first of their remaining eight games as the Bluebirds face potential crucial promotion showdowns with leaders Queens Park Rangers and play-off chasing Burnley on the final day of the season.
"There are a good set of lads here who are disappointed with what is going on," said Parkin.
"But it is a big eight games for us now. We must put everything that has happened so far behind us. This has now turned into an eight-game season for us."
Source: BBC Sport
Source: BBC Sport